By EDWARD D. GRAVILL, F.C.S., F.R.M.S.
Now that a supply of this reputed substitute for sugar has been placed
upon the London market, it will doubtless have attracted the attention
of many pharmacists, and as information having reference to its
characters and properties is as yet somewhat scarce, the following
notes may be of interest.
The sample to which these notes refer represents, I believe, a portion
of the first supply that has been offered to us as a commercial
article, and may therefore be taken to represent the same as it at
present occurs in commerce. I think it desirable to call attention to
this fact, because of the wide difference I have seen in other samples
obtained, I think, by special request some weeks ago, and which do not
favorably correspond with the sample under consideration, being much
more highly colored, and in comparison having a very strong odor.
Saccharin now occurs as a very pale yellow, nearly white, amorphous
powder, free from grittiness, but giving a distinct sensation of
roughness when rubbed between the fingers. It is not entirely free
from odor, but this is very slight, and not at all objectionable,
reminding one of a very slight flavor of essential oils of almonds.
Its taste is intensely sweet and persistent, which in the raw state is
followed by a slight harshness upon the tongue and palate. The
sweetness is very distinct when diluted to 1 in 10,000. Under the
microscope it presents no definite form of crystallization.
A temperature of 100° C, even if continued for some time, has no
perceptible effect upon saccharin; it loses no weight, and undergoes
no physical change. It fuses at a temperature of from 118° to 120° C.,
and at 150° C. forms a clear light yellow liquid, which boils a few
degrees higher. At the latter temperature dense white fumes appear,
and a condensation of tufts of acicular crystals (some well defined)
is found upon the cool surface of the apparatus. These crystals,
except for a slight sweetness of taste, correspond in characters and
tests to benzoic acid. The sweet flavor, I think, may be due to the
presence of a very small quantity of undecomposed saccharin, carried
mechanically with the fumes. The escaping vapors, which are very
irritable, and give a more decided odor of hydride of benzole than the
powder itself, also communicate a very distinct sensation of sweetness
to the back part of the palate. Heated over the flame, with free
access of air, saccharin carbonizes and burns with a dull yellow smoky
flame, leaving a residue amounting to 0.65 per cent. of sodium salts.
It does not reduce an alkaline copper solution, but, like glycerine,
liberates boracic acid from borax, the latter salt dissolving
saccharin readily in aqueous solution, due no doubt to a displacement
of the boracic acid.
The strong acids, either hot or cold, show no characteristic color
reaction; the compound enters solution at the boiling point of the
acid, and in the case of hydrochloric shows a white granular
separation on cooling. Sulphuric acid develops an uncharacteristic
light brown color.
The compound, like most of the organic acids, shows a characteristic
reaction with ferro and ferrid cyanide of potassium. In the former
case no change is perceptible until boiled when a greenish white
turbidity appears, with the liberation of small quantities of
hydrocyanic acid. In the latter case a trace also of this acid is set
free, with the formation of a very distinct green solution, the latter
reaction being very perceptible with a few drops of a 1 in 1,000
solution of saccharin in water. Heated with lime, very distinct odors
of benzoic aldehyde are developed.
Saccharin possesses very decided acid properties, and combines readily
with alkalies or alkaline carbonates, forming anhydro-ortho
sulphamine-benzoates of the same, in the latter case at the expense of
the carbonic anhydride, causing strong effervescence. These
combinations are very soluble in water, the alkaline carbonate thus
forming a ready medium for the solution of this acid, which alone is
so sparingly soluble. Another advantage of some importance is that,
while the harshness of flavor perceptible in a simple solution of the
acid is destroyed, the great sweetness appears to be distinctly
intensified and refined.
The following shows the solubility of saccharin in the various liquids
quoted, all, with the exception of the boiling water, being taken at
60° F.:
Boiling water 0.60 parts per 100 by volume.
Cold water 0.20 " " "
Alcohol 0.800 4.25 " " "
Rectified spirit 0.838 3.20 " " "
Ether 0.717 1.00 " " "
Chloroform 1.49 0.20 " " "
Benzene 0.40 " " "
Petroleum ether insoluble.
It is also sparingly soluble in glycerin and fixed oils, and to a
greater or less extent in volatile oils. Benzoic aldehyde dissolves
saccharin in large quantities.
I was somewhat disappointed at the slight solubility of saccharin in
ether, as it has been repeatedly stated to be very soluble in that
liquid.
The quantity of saccharin required to communicate an agreeable degree
of sweetness, like sugar, differs with the material to be sweetened;
but from half to one and half grains, according to taste, will be
found sufficient for an ordinary breakfast cup full of tea or coffee
infusion.--_Pharm. Jour._
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