CHAPTER III._The handbook of soap manufacture

RAW MATERIALS USED IN SOAP-MAKING.

_Fats and Oils--Waste Fats--Fatty Acids--Less-known Oils and

Fats of Limited Use--Various New Fats and Oils Suggested for

Soap-making--Rosin--Alkali (Caustic and

Carbonated)--Water--Salt--Soap-stock._

_Fats and Oils._--All animal and vegetable oils and fats intended for

soap-making should be as free as possible from unsaponifiable matter, of

a good colour and appearance, and in a sweet, fresh condition. The

unsaponifiable matter naturally present as cholesterol, or phytosterol,

ranges in the various oils and fats from 0.2 to 2.0 per cent. All oils

and fats contain more or less free acidity; but excess of acidity,

though it may be due to the decomposition of the glyceride, and does not

always denote rancidity, is undesirable in soap-making material.

Rancidity of fats and oils is entirely due to oxidation, in addition to

free acid, aldehydes and ketones being formed, and it has been proposed

to estimate rancidity by determining the amount of these latter

produced. It is scarcely necessary to observe how very important it is

that the sampling of fats and oils should be efficiently performed, so

that the sample submitted to the chemist may be a fairly representative

average of the parcel.

In the following short description of the materials used, we give, under

each heading, figures for typical samples of the qualities most suitable

for soap-making.

_Tallows._--Most of the imported tallow comes from America, Australia

and New Zealand. South American mutton tallow is usually of good

quality; South American beef tallow is possessed of a deep yellow colour

and rather strong odour, but makes a bright soap of a good body and

texture. North American tallows are, as a general rule, much paler in

colour than those of South America, but do not compare with them in

consistence. Most of the Australasian tallows are of very uniform

quality and much in demand.

Great Britain produces large quantities of tallow which comes into the

market as town and country tallow, or home melt. Owing to the increasing

demand for edible fat, much of the rough fat is carefully selected,

rendered separately, and the product sold for margarine-making.

Consequently the melted tallow for soap-making is of secondary

importance to the tallow melter.

The following are typical samples of tallow:--

_______________________________________________________________________

| | | | |

|_________________________________|________________|___________|________|

| | | | |

| Australian mutton | 285 | 0.85 | 45 |

| Australian mutton | 284.4 | 0.48 | 48.3 |

| Australian beef | 284.2 | 1.68 | 43.9 |

| Australian beef | 283.6 | 0.85 | 42.6 |

| Australian mixed | 285.1 | 3.52 | 44 |

| Australian mixed | 284.6 | 1.89 | 43.5 |

| South American mutton | 284.5 | 1.11 | 47 |

| South American mutton | 285 | 0.90 | 47.4 |

| South American beef | 284.7 | 0.81 | 45 |

| South American beef | 284 | 0.94 | 44 |

| North American mutton | 284.3 | 1.32 | 44 |

| North American mutton | 85 | 2.18 | 43.2 |

| North American beef, fine | 284.5 | 1.97 | 41.5 |

| North American beef, good | 283.8 | 4.30 | 42 |

| North American ordinary | 285.2 | 5.07 | 41.75 |

| North American prime city | 286 | 1.01 | 41.2 |

| Selected English mutton | 283.9 | 1.45 | 47 |

| Selected English beef | 284.2 | 2.40 | 44 |

| Home-rendered or country tallow | 284.6 | 5.1 | 43 |

| Town tallow | 285.3 | 7.4 | 42.5 |

|_________________________________|________________|___________|________|

Tallow should absorb from 39 to 44 per cent. iodine.

_Lard._--Lard is largely imported into this country from the United

States of America. The following is a typical sample of American hog's

fat offered for soap-making:--

________________________________________________________

| | | | |

| | Per Cent. | | at 60° C. |

|________________|_________________|________|____________|

| | | | |

| 286 | 0.5 | 37.5 | 1.4542 |

|________________|_________________|________|____________|

Lard should absorb 59 to 63 per cent. iodine.

_Cocoa-nut Oil._--The best known qualities are Cochin and Ceylon oils,

which are prepared in Cochin (Malabar) or the Philippine Islands and

Ceylon respectively.

The dried kernels of the cocoa-nut are exported to various ports in

Europe, and the oil obtained comes on the market as Continental Coprah

Oil, with the prefix of the particular country or port where it has been

crushed, _e.g._, Belgian, French and Marseilles Coprah Oil. Coprah is

also imported into England, and the oil expressed from it is termed

English Pressed Coprah.

The following are typical examples from bulk:--

_________________________________________________________________________

| | | | | |

| | | Per Cent. | | at 25° C. |

|________________|________________|_________________|________|____________|

| | | | | |

| Cochin oil | 215.5 | 1.5 | 23.5 | 1.4540 |

| Cochin oil | 214.3 | 2.6 | 22.1 | 1.4541 |

| Ceylon oil | 214.6 | 5.47 | 23 | 1.4535 |

| Ceylon oil | 216 | 3.95 | 22.75 | 1.4535 |

| Belgian coprah | 214.2 | 1.65 | 23 | 1.4541 |

| Belgian coprah | 215 | 2.60 | 22.1 | 1.4540 |

| French coprah | 214.2 | 6.55 | 23 | 1.4535 |

| French coprah | 214.8 | 7.42 | 22 | 1.4540 |

| Pressed coprah | 215.8 | 7.45 | 22.2 | 1.4542 |

| Pressed coprah | 216 | 9.41 | 22 | 1.4555 |

|________________|________________|_________________|________|____________|

Cocoa-nut oil should absorb 8.9 to 9.3 per cent. iodine.

_Palm-nut Oil._--The kernels of the palm-tree fruit are exported from

the west coast of Africa to Europe, and this oil obtained from them.

Typical samples of English and Hamburg oils tested:--

_________________________________________________________

| | | | |

| | Per Cent. | | at 25° C. |

|________________|_________________|________|____________|

| | | | |

| 225 | 4.4 | 24 | 1.4553 |

| 227 | 7.7 | 23.8 | 1.4553 |

|________________|_________________|________|____________|

Palm-nut oil should absorb 10 to 13 per cent. iodine.

_Olive Oil._--The olive is extensively grown in Southern Europe and in

portions of Asia and Africa bordering the Mediterranean Sea. The fruit

of this tree yields the oil.

The free fatty acid content of olive oil varies very considerably. Very

fine oils contain less than 1 per cent. acidity; commercial oils may be

graded according to their free acidity, _e.g._, under 5 per cent., under

10 per cent., etc., and it entirely depends upon the desired price of

the resultant soap as to what grade would be used. The following is a

typical sample for use in the production of high-class toilet soap:--

_________________________________________________________

| | | | |

| | Per Cent. | | at 15° C. |

|________________|_________________|________|____________|

| | | | |

| 288 | 1.8 | 21 | 1.4704 |

|________________|_________________|________|____________|

Olive oil should absorb 80 to 83 per cent. iodine.

_Olive-kernel oil_, more correctly termed _Sulphur olive oil_.

The amount of free fatty acids is always high and ranges from 40-70 per

cent., and, of course, its glycerol content is proportionately variable.

The free acidity increases very rapidly, and is, doubtless, due to the

decomposition of the neutral oil by the action of hydrolytic ferment.

A representative sample of a parcel tested:--

_______________________________________________

| | | |

| Saponification | Acidity | Refractive |

| Equivalent. | (as Oleic Acid) | Index |

| | Per Cent. | at 20° C. |

|________________|_________________|____________|

| | | |

| 298 | 40.96 | 1.4666 |

|________________|_________________|____________|

_Palm oil_ is produced from the fruit of palm trees, which abound along

the west coast of Africa. Lagos is the best quality, whilst Camaroons,

Bonny, Old Calabar and New Calabar oils are in good request for

bleaching purposes.

Analysis of typical samples of crude palm oil has given:--

_________________________________________________________

| | | | |

|________________|_________________|________|_____________|

| | | | |

| 278 | 10.7 | 45 | 1.6 |

| 280 | 31.2 | 44.5 | 2.8 |

|________________|_________________|________|_____________|

Palm oil should absorb 51 to 56 per cent. iodine.

In the lower qualities we have examples of the result of hydrolytic

decomposition by enzymes, the free acidity often amounting to 70 per

cent.

_Cotton-seed Oil._--This oil is expressed from the seeds separated from

the "wool" of the various kinds of cotton tree largely cultivated in

America and Egypt.

In its crude state cotton-seed oil is a dark fluid containing

mucilaginous and colouring matter, and is not applicable for

soap-making. The following figures are representative of well-refined

cotton-seed oils:--

_________________________________________________________________________

| | | | | |

| at 15° C. | | Per Cent. | | at 20° C. |

|___________|________________|_________________|________|____________|

| | | | | |

| 0.9229 | 290 | 0.24 | 33.6 | 1.4721 |

| 0.924 | 299 | 0.39 | 35 | 1.4719 |

|___________|________________|_________________|________|____________|

Cotton-seed oil should absorb 104 to 110 per cent. iodine.

_Cotton-seed Stearine._--The product obtained by pressing the deposit

which separates on chilling refined cotton-seed oil.

A typical sample tested:--

___________________________________________

| | | |

| Saponification | Acidity | Titre, |

| Equivalent. | (as Oleic Acid) | °C. |

| | Per Cent. | |

|________________|_________________|________|

| | | |

| 285.1 | 0.05 | 38 |

|________________|_________________|________|

_Arachis Oil._--The earth-nut or ground-nut, from which arachis oil is

obtained, is extensively cultivated in North America, India and Western

Africa. Large quantities are exported to Marseilles where the oil is

expressed. Arachis oil enters largely into the composition of Marseilles

White Soaps.

Representative samples of commercial and refined oils tested:--

______________________________________________________________________

| | | | | | |

| | at 15° C. | Equi- | Acid) | °C. | at 20° C. |

|____________|___________|___________|___________|________|____________|

| | | | | | |

| Commercial | 0.9184 | 298 | 2.6 | 28.6 | |

| Refined | 0.9205 | 285 | 0.22 | 24.0 | 1.4712 |

|____________|___________|___________|___________|________|____________|

Arachis oil should absorb 90 to 98 per cent. iodine.

_Maize Oil._--America (U.S.) produces very large quantities of maize

oil.

Typical samples of crude and refined oil gave these figures:--

______________________________________________________________________

| | | | | | |

| | at 15° C. | Equi- | Acid) | °C. | at 20° C. |

|____________|___________|___________|___________|________|____________|

| | | | | | |

| Crude | 0.9246 | 294 | 1.41 | 15 | |

| Refined | 0.9248 | 294.1 | 0.40 | 17.2 | 1.4766 |

|____________|___________|___________|___________|________|____________|

Maize oil should absorb 120 to 128 per cent. iodine.

_Sesame Oil._--Sesame oil is very largely pressed in Southern France

from the seeds of the sesame plant which is cultivated in the Levant,

India, Japan and Western Africa.

A fairly representative sample of French expressed oil tested:--

____________________________________________________________________

| | | | | |

| at 15° C. | | Per Cent. | | at 20° C. |

|___________|________________|_________________|________|____________|

| | | | | |

| 0.9227 | 295.2 | 1.84 | 22.8 | 1.4731 |

|___________|________________|_________________|________|____________|

Sesame oil should absorb 108 to 110 per cent. iodine.

_Linseed Oil._--Russia, India, and Argentine Republic are the principal

countries which extensively grow the flax plant, from the seeds of which

linseed oil is pressed. It is used to a limited extent in soft-soap

making.

A good sample gave on analysis:--

____________________________________________________________________

| | | | | |

| at 15° C. | | Per Cent. | | at 15° C. |

|___________|________________|_________________|________|____________|

| | | | | |

| 0.935 | 292 | 1.2 | 20 | 1.4840 |

|___________|________________|_________________|________|____________|

Linseed oil should absorb 170 to 180 per cent. iodine.

_Hemp-seed oil_ is produced from the seeds of the hemp plant which grows

in Russia. This oil is used in soft soap-making, more particularly on

the Continent.

A typical sample gave the following figures:--

__________________________________________________

| | | | |

| at 15° C. | | | |

|___________|________________|________|____________|

| | | | |

| 0.926 | 292.6 | 15.8 | 143 |

|___________|________________|________|____________|

_Sunflower oil_ is produced largely in Russia.

A specimen tested:--

____________________________________________________________________

| | | | | |

| at 15° C. | | Per Cent. | | |

|___________|________________|_________________|________|____________|

| | | | | |

| 0.9259 | 290.7 | 0.81 | 17 | 126.2 |

|___________|________________|_________________|________|____________|

_Castor Oil._--The castor oil plant is really a native of India, but it

is also cultivated in the United States (Illinois) and Egypt.

A typical commercial sample tested:--

________________________________________________________________________

| | | | | | |

| Equi- | Acid) | °C. | | [alpha]_{D} | at 25° C. |

|___________|___________|________|____________|_____________|____________|

| | | | | | |

| 310 | 1.5 | 2.8 | 84.1 | + 4° 50' | 1.4787 |

|___________|___________|________|____________|_____________|____________|

_Fish and Marine Animal Oils._--Various oils of this class have, until

recently, entered largely into the composition of soft soaps, but a

demand has now arisen for soft soaps made from vegetable oils.

We quote a few typical analyses of these oils:--

_________________________________________________________________________

| | | | | | |

|__________________|__________|__________|___________|________|___________|

| | | | | | |

| Pale seal oil | 0.9252 | 289 | 0.947 | 15.5 | 0.8 |

| Straw seal oil | 0.9231 | 288 | 4.77 | 15.8 | 1.2 |

| Brown seal oil | 0.9253 | 291 | 16.38 | 16.2 | 1.9 |

| Whale oil | 0.9163 | 297 | 1.49 | 16.1 | 1.8 |

| Dark whale oil | 0.9284 | 303 | 12.60 | 21.8 | 2.4 |

| Japan fish oil | 0.9336 | 296 | 4.79 | 26 | 0.67 |

| Japan fish oil | 0.9325 | 302 | 10.43 | 28 | 1.55 |

| Brown cod oil | 0.9260 | 313 | 14.91 | 21.8 | 1.9 |

| Pure herring oil | 0.9353 | 288 | 11.39 | 21.6 | 1.5 |

| Kipper oil | 0.9271 | 297 | 5.14 | 22.7 | 3.25 |

|__________________|__________|__________|___________|________|___________|

_Waste Fats._--Under this classification may be included marrow fat,

skin greases, bone fats, animal grease, melted stuff from hotel and

restaurant refuse, and similar fatty products. The following is a fair

typical selection:--

_______________________________________________________________

| | | | |

|___________________|________________|_________________|________|

| | | | |

| Marrow fat | 283.3 | 3.6 | 38.7 |

| White skin grease | 287.2 | 4.3 | 36.4 |

| Pale skin grease | 286.3 | 9.87 | 35.7 |

| Pale bone fat | 289.7 | 8.8 | 40.7 |

| Brown bone fat | 289.1 | 11.0 | 41 |

| Brown bone fat | 292 | 20.5 | 40.2 |

| Animal grease | 289.4 | 38.1 | 40.4 |

| Melted stuff | 286.3 | 12.8 | 37.7 |

|___________________|________________|_________________|________|

The materials in the above class require to be carefully examined for

the presence of unsaponifiable matter, lime salts and other impurities.

_Fatty Acids._--We have already described the various methods of

liberating fatty acids by hydrolysis or saponification.

Under this heading should also be included stearines produced by

submitting distilled fat to hydraulic pressure, the distillates from e

from unsaponifiable matter, cocoa-nut oleine, a bye-product from the

manufacture of edible cocoa-nut butter and consisting largely of free

acids, and palm-nut oleine obtained in a similar manner from palm-nut

oil.

These are all available for soap-making.

LESS-KNOWN OILS AND FATS OF LIMITED USE.

_Shea Butter._--Shea butter is extracted from the kernels of the _Bassia

Parkii_ and exported from Africa and Eastern India. This fat is somewhat

tough and sticky, and the amount of unsaponifiable matter present is

sometimes considerable. Samples examined by us gave the following

data:--

_______________________________________________________________

| | | | |

| | Per Cent. | | at 60° C. |

|________________|_________________|________|___________________|

| | | | |

| 313 | 8.2 | 53.2 | 1.4566 |

| 303 | 7.33 | 53 | 1.4558 |

|________________|_________________|________|___________________|

_Mowrah-seed Oil._--The mowrah-seed oil now offered for soap-making is

derived from the seeds of _Bassia longifolia_ and _Bassia latifolia_. It

is largely exported from India to Belgium, France and England. The

following are the results of some analyses made by us:--

_________________________________________________________

| | | | |

| | Per Cent. | | at 60° C. |

|________________|_________________|________|____________|

| | | | |

| 291 | 10 | 43.4 | 1.4518 |

| 291.5 | 7.1 | 42.7 | |

| 291.2 | 9.9 | 43.8 | |

| 292 | 11.26 | 40.5 | |

|________________|_________________|________|____________|

_Chinese vegetable tallow_ is the name given to the fat which is found

coating the seeds of the "tallow tree" (_Stillingia sebifera_) which is

indigenous to China and has been introduced to India where it

flourishes. The following is a typical sample:--

_____________________________________

| | | |

| Saponification | Acidity | Titre, |

| Equivalent | Per Cent. | °C. |

|________________|___________|________|

| | | |

| 280.2 | 5.24 | 52.5 |

|________________|___________|________|

The seeds of the "tallow tree" yield an oil (stillingia oil) having

drying properties.

_Borneo Tallow._--The kernels of several species of _Hopea_ (or

_Dipterocarpus_), which flourish in the Malayan Archipelago, yield a fat

known locally as Tangawang fat. This fat is moulded (by means of bamboo

canes) into the form of rolls about 3 inches thick, and exported to

Europe as Borneo Tallow.

A sample tested by one of us gave the following data:--

___________________________________________

| | | |

| Saponification | Acidity | Titre, |

| Equivalent. | (as Oleic Acid) | °C. |

| | Per Cent. | |

|________________|_________________|________|

| | | |

| 292 | 36 | 50.8 |

|________________|_________________|________|

_Kapok oil_ is produced from a tree which is extensively grown in the

East and West Indies. The Dutch have placed it on the market and the

figures given by Henriques (_Chem. Zeit._, 17, 1283) and Philippe

(_Monit. Scient._, 1902, 730), although varying somewhat, show the oil

to be similar to cotton-seed oil.

VARIOUS NEW FATS AND OILS SUGGESTED FOR SOAP-MAKING.

_Carapa_ or _Andiroba oil_, derived from the seeds of a tree (_Carapa

Guianensis_) grown in West Indies and tropical America, has been

suggested as suitable for soap-making. Deering (_Imperial Institute

Journ._, 1898, 313) gives the following figures:--

____________________________________________

| | | |

| Saponification | Acidity | Melting Point |

| Equivalent | Per Cent. | of Fatty |

| | | Acids, °C. |

|________________|___________|_______________|

| | | |

| 287 | 12 | 89 |

|________________|___________|_______________|

Another observer (_Rev. Chem. Ind._, 13, 116) gives the setting point of

the fatty acids as 56.4° C.

_Candle-nut oil_ obtained from the seeds of a tree flourishing in India

and also the South Sea Islands.

The following figures have been published:--

_____________________________________________________________________________

| | | | |

| alent.[1] | °C. | | |

|___________|_______|____________|____________|_______________________________

| | | | |

| 299-304.9 | 13 | 136.3-139.3| De Negri |_Chem. Centr._, 1898, p. 493.

| 291 | | 163.7 | Lewkowitsch|_Chem. Revue_, 1901, p. 156.

| 296 | 12.5 | 152.8 | Kassler |_Farben-Zeitung_, 1903, p. 359.

|___________|_______|____________|____________|_______________________________

_Curcas oil_ is produced in Portugal from the seeds of the "purging nut

tree," which is similar to the castor oil plant, and is cultivated in

Cape Verde Islands and other Portuguese Colonies.

The following data have been observed:--

______________________________________________________________________________

| | | | |

| alent.[2] | °C. | | |

|___________|_______|____________|____________|_______________________________

| | | | |

| 291.4 | 0.36 | 99.5 | Archbut |_J. S. C. Ind._, 1898, p. 1010.

| 290.3 | 4.46 | 98.3 | Lewkowitsch|_Chem. Revue_, 1898, p. 211.

| 283.1 | 0.68 | 107.9 | Klein |_Zeits. angew. Chem._,

| | | | | 1898, p. 1012.

|___________|_______|____________|____________|_______________________________

The titre is quoted by Lewkowitsch as 28.6° C.

_Goa butter_ or _Kokum butter_ is a solid fat obtained from the seeds of

_Garcinia indica_, which flourishes in India and the East Indies.

Crossley and Le Sueur (_Journ. Soc. Chem. Industry_, 1898, p. 993)

during an investigation of Indian oils obtained these results:--

_________________________________________

| | | |

| Saponification | Acidity | Iodine No. |

| Equivalent.[3] | Per Cent. | |

|________________|___________|____________|

| | | |

| 300 | 7.1 | 34.2 |

|________________|___________|____________|

_Safflower oil_ is extracted from the seeds of the _Carthamus

tinctorius_, which, although indigenous to India and the East Indies, is

extensively cultivated in Southern Russia (Saratowa) and German East

Africa. Its use has been suggested for soft-soap making. The following

figures have been published:--

____________________________________________________________________________

| | | | |

| | Equiv- | No. | |

|_________|_________|________|_____________|_________________________________

| | | | |

| | 293.7 | 142.2 | Fendler |_Chem. Zeitung_, 1904, p. 867.

|_________|_________|________|_____________|_________________________________

_Maripa fat_ is obtained from the kernels of a palm tree flourishing in

the West Indies, but, doubtless, the commercial fat is obtained from

other trees of the same family. It resembles cocoa-nut oil and gives the

following figures:--

___________________________________________________________________________

| | | | |

|__________|________|___________|___________|_______________________________

| | | | |

| 217 | 9.49 | 25 | Bassière |_J. S. C. Ind._, 1903, p. 1137.

|__________|________|___________|___________|_______________________________

_Niam fat_, obtained from the seeds of _Lophira alata_, which are found

extensively in the Soudan. The fat, as prepared by natives, has been

examined by Lewkowitsch, and more recently Edie has published the

results of an analysis. The figures are as follows:--

__________________________________________________________________________

| | | | |

| Equiv- | | No. | |

| alent.[6] | °C. | | |

|___________|_______|________|____________|_______________________________

| | | | |

| 295.1 | 78.12 | 42.5 | Lewkowitsch|_J. S. C. Ind._, 1907, p. 1266.

| 287.7 | 75.3 | | Edïe. |_Quart. J. Inst. Comm.

|___________|_______|________|____________|_______________________________

_Cohune-nut oil_ is produced from the nuts of the cohune palm, which

flourishes in British Honduras. This oil closely resembles cocoa-nut and

palm-nut oils and is stated to saponify readily and yield a soap free

from odour. The following figures, obtained in the Laboratory of the

Imperial Institute, are recorded in the official _Bulletin_, 1903, p.

25:--

________________________________________________

| | | |

| Saponification | Iodine No. | Melting Point of |

| Equivalent. | | Fatty Acids, °C. |

|________________|____________|__________________|

| | | |

| 253.9-255.3 | 12.9-13.6 | 27-30 |

|________________|____________|__________________|

_Mafoureira_ or _Mafura tallow_ from the nuts of the mafoureira tree,

which grows wild in Portuguese East Africa. The following figures are

published:--

______________________________________________________________________________

| | | |

| Saponi- | | |

| fication | | Iodine | References.

| Equi- | | No. |

| valent. | | |

|_____________|________________|___________|___________________________________

| | Titre, °C. | |

| 253.8 | 44-48 | 46.14 | De Negri and Fabris, _Annal. del

| | | | Lab. Chim. Delle Gabelle_,

| | | | 1891-2, p. 271.

| | Acidity | |

| | (as Oleic Acid)| |

| | Per Cent. | | _Bulletin Imp. Inst._,

| 232.8-233.7 | 21.26 | 47.8-55.8 | 1903, p. 27.

|_____________|________________|___________|___________________________________

_Pongam oil_, obtained from the beans of the pongam tree, which

flourishes in East India, has been suggested as available for the soap

industry, but the unsaponifiable matter present would militate against

its use. Lewkowitsch (_Analyst_, 1903, pp. 342-44) quotes these

results:--

_____________________________________________________________________

| | | | | |

|_________________|____________|________|___________|_________________|

| | | | | |

| Oil extracted | 315 | 94 | 3.05 | 9.22 |

| Indian specimen | 306 | 89.4 | 0.5 | 6.96 |

|_________________|____________|________|___________|_________________|

_Margosa oil_ is obtained from the seeds of _Melia azedarach_, a tree

which is found in most parts of India and Burma.

Lewkowitsch (_Analyst_, 1903, pp. 342-344) gives these figures:--

__________________________________

| | | |

| Saponification | Iodine | Titre, |

| Equivalent.[8] | No. | °C. |

|________________|________|________|

| | | |

| 284.9 | 69.6 | 42 |

|________________|________|________|

_Dika fat_ or _Wild Mango oil_ is obtained from the seed kernels of

various kinds of _Irvingia_ by boiling with water. Lemarié (_Bulletin

Imp. Inst._, 1903, p. 206) states that this fat is used in the place of

cocoa-nut oil in the manufacture of soap. Lewkowitsch (_Analyst_, 1905,

p. 395) examined a large sample of dika fat obtained from seeds of

_Irvingia bateri_ (South Nigeria) and gives the following data:--

____________________________________________________

| | | | |

| Equivalent.[9] | No. | °C. | Per Cent. |

|________________|________|________|_________________|

| | | | |

| 229.4 | 5.2 | 34.8 | 0.73 |

|________________|________|________|_________________|

_Baobab-seed Oil._--Balland (_Journ. Pharm. Chem._, 1904, p. 529,

abstracted in _Journ. Soc. Chem. Ind._, 1905, p. 34) states that the

natives of Madagascar extract, by means of boiling water, from the seeds

of the baobab tree, a whitish solid oil, free from rancidity, and

possessed of an odour similar to Tunisian olive oil. He suggests that it

may, with advantage, replace cocoa-nut oil in soap manufacture.

_Persimmon-seed Oil._--Lane (_J. S. C. Ind._, 1905, p. 390) gives

constants for this oil which he describes as semi-drying, of brownish

yellow colour, and having taste and odour like pea-nut (arachis) oil.

The following are taken from Lane's figures:--

___________________________________

| | | |

| Saponification | Iodine | Titre, |

| Equivalent.[10] | No. | °C. |

|_________________|________|________|

| | | |

| 298.4 | 115.6 | 20.2 |

|_________________|________|________|

_Wheat oil_, extracted from the wheat germ by means of solvents, has

been suggested as applicable for soap-making (H. Snyder, abstr. _J. S.

C. Ind._, 1905, p. 1074). The following figures have been published:--

_______________________________________________________________________________

| | | | | |

| Equiv- | Per | No. | | |

|___________|_________|________|________|_____________|________________________

| | | | | |

| 306 | 5.65 | 115.17 | 29.7 | De Negri. | _Chem. Zeit._, 1898

| | | | | | 1898, p. 1155).

| 297 | 20 | 115.64 | | Frankforter | _J. Amer. C. Soc._,

| | | | | | 1899, p. 1030).

|___________|_________|________|________|_____________|________________________

_Tangkallah fat_, from the seeds of a tree growing in Java and the

neighbouring islands, is suitable for soap-making. Schroeder (_Arch.

Pharm._, 1905, 635-640, abstracted in _J. S. C. Ind._, 1906, p. 128)

gives these values:--

_______________________________________________________

| | | | |

|________________|___________|________|_________________|

| | | | |

| 209 | 1.67 | 2.28 | 1.44 |

|________________|___________|________|_________________|

It is a hard fat, nearly white, possessing neither taste nor

characteristic odour and solidifying at about 27° C.

_Oil of Inoy-kernel._--(_Bulletin Imp. Inst._, 1906, p. 201). The seeds

of Poga oleosa from West Africa yield on extraction an oil which gives

the figures quoted below, and is suggested as a soap-maker's material:--

__________________________________

| | | |

| Saponification | Iodine | Titre, |

| Equivalent. | No. | °C. |

|________________|________|________|

| | | |

| 304 | 89.75 | 22 |

|________________|________|________|

ROSIN.

Rosin is the residuum remaining after distillation of spirits of

turpentine from the crude oleo-resin exuded by several species of the

pine, which abound in America, particularly in North Carolina, and also

flourish in France and Spain. The gigantic forests of the United States

consist principally of the long-leaved pine, _Pinus palustris

(Australis)_, whilst the French and Spanish oleo-resin is chiefly

obtained from _Pinus pinaster_, which is largely cultivated.

Rosin is a brittle, tasteless, transparent substance having a smooth

shining fracture and melting at about 135° C. (275° F.). The American

variety possesses a characteristic aromatic odour, which is lacking in

those from France and Spain. It is graded by samples taken out of the

top of every barrel, and cut into 7/8 of an inch cubes, which must be

uniform in size--the shade of colour of the cube determines its grade

and value.

The grades are as follows:--

W. W. (Water white.)

W. G. (Window glass.)

N. (Extra pale.)

M. (Pale.)

K. (Low pale.)

I. (Good No. 1.)

H. (No. 1.)

G. (Low No. 1.)

F. (Good No. 2.)

E. (No. 2.)

D. (Good strain.)

C. (Strain.)

B. (Common strain.)

A. (Common.)

Unsaponifiable matter is present in rosin in varying amounts.

Below are a few typical figures taken from a large number of collated

determinations:--

________________________________________________________________

| | | | | |

|________________|________________|__________|__________|________|

| | | | | |

| American W. W. | 330.5 | 169.7 | 119.1 | 126.9 |

| American N. | 312.3 | 179.6 | 161.4 | 137.8 |

| French | 320.5 | 175 | 168 | 120.7 |

| Spanish | 313.4 | 179 | 160 | 129.8 |

|________________|________________|__________|__________|________|

ALKALI (CAUSTIC AND CARBONATED).

The manufacture of alkali was at one time carried on in conjunction with

soap-making, but of late years it has become more general for the soap

manufacturer to buy his caustic soda or carbonated alkali from the

alkali-maker.

Although there are some alkali-makers who invoice caustic soda and soda

ash in terms of actual percentage of sodium oxide (Na_{2}O), it is the

trade custom to buy and sell on what is known as the English degree,

which is about 1 per cent. higher than this.

The English degree is a survival of the time when the atomic weight of

sodium was believed to be twenty-four instead of twenty-three, and,

since the error on 76 per cent. Na_{2}O due to this amounts to about 1

per cent., may be obtained by adding this figure to the sodium oxide

really present.

_Caustic soda_ (sodium hydrate) comes into commerce in a liquid form as

90° Tw. (and even as high as 106° Tw.), and other degrees of dilution,

and also in a solid form in various grades as 60°, 70°, 76-77°, 77-78°.

These degrees represent the percentage of sodium oxide (Na_{2}O) present

plus the 1 per cent. The highest grade, containing as it does more

available caustic soda and less impurities, is much more advantageous in

use.

_Carbonate of soda_ or _soda ash_, 58°, also termed "light ash," and

"refined alkali". This is a commercially pure sodium carbonate

containing about 0.5 per cent. salt (NaCl). The 58° represents the

English degrees and corresponds to 99 per cent. sodium carbonate

(Na_{2}CO_{3}).

_Soda ash_, 48°, sometimes called "caustic soda ash," often contains

besides carbonate of soda, 4 per cent. caustic soda (sodium hydrate),

and 10 per cent. salt (sodium chloride), together with water and

impurities.

The 48 degrees refers to the amount of alkali present in terms of sodium

oxide (Na_{2}O), but expressed as English degrees.

_Caustic potash_ (potassium hydrate) is offered as a liquid of 50-52° B.

(98-103° Tw.) strength, and also in solid form as 75-80° and 88-92°. The

degrees in the latter case refer to the percentage of potassium hydrate

(KHO) actually present.

_Carbonate of Potash._--The standard for refined carbonate of potash is

90-92 per cent. of actual potassium carbonate (K_{2}CO_{3}) present,

although it can be obtained testing 95-98 per cent.

OTHER MATERIALS.

_Water._--Water intended for use in soap-making should be as soft as

possible. If the water supply is hard, it should be treated chemically;

the softening agents may be lime and soda ash together, soda ash alone,

or caustic soda. There are many excellent plants in vogue for water

softening, which are based on similar principles and merely vary in

mechanical arrangement. The advantages accruing from the softening of

hard water intended for steam-raising are sufficiently established and

need not be detailed here.

_Salt_ (sodium chloride or common salt, NaCl) is a very important

material to the soap-maker, and is obtainable in a very pure state.

Brine, or a saturated solution of salt, is very convenient in

soap-making, and, if the salt used is pure, will contain 26.4 per cent.

sodium chloride and have a density of 41.6° Tw. (24.8° B.).

The presence of sulphates alters the density, and of course the sodium

chloride content.

Salt produced during the recovery of glycerine from the spent lyes often

contains sulphates, and the density of the brine made from this salt

ranges higher than 42° Tw. (25° B.).

_Soapstock._--This substance is largely imported from America, where it

is produced from the dark-coloured residue, termed mucilage, obtained

from the refining of crude cotton-seed oil. Mucilage consists of

cotton-seed oil soap, together with the colouring and resinous

principles separated during the treatment of the crude oil. The

colouring matter is removed by boiling the mucilage with water and

graining well with salt; this treatment is repeated several times until

the product is free from excess of colour, when it is converted into

soap and a nigre settled out from it.

Soapstock is sold on a fatty acid basis; the colour is variable.

FOOTNOTES:

[1] Calculated by us from saponification value.

[2] Calculated by us from saponification value.

[3] Calculated by us from saponification value.

[4] Calculated by us from saponification value.

[5] Calculated by us from saponification value.

[6] Calculated by us from saponification value.

[7] Calculated by us from saponification value.

[8] Calculated by us from saponification value.

[9] Calculated by us from saponification value.

[10] Calculated by us from saponification value.

[11] Calculated by us from saponification value.

[12] Calculated by us from saponification value.