Beeswax is a peculiar waxy substance secreted only by bees, and
consisting of 80.2 per cent. carbon, 13.4 per cent. hydrogen, and 6.4
per cent. oxygen. It is a mixture of myricine, cerotic acid, and
cerolein, the first of which is insoluble in boiling alcohol, the
second is soluble in hot alcohol and crystallizes out on cooling,
while the third remains dissolved in cold alcohol.
Although we are unable to produce real beeswax artificially, there are
many imitations which are made use of to adulterate the genuine
article, and their detection is a matter of considerable difficulty.
Huebl says (_Dingl. Jour._, p. 338) that the most reliable method of
estimating the adulteration of beeswax is that proposed by Becker, and
known as the saponification method.
The quantity of potassic hydrate required to saponify one gramme or 15
grains of pure beeswax varies from 97 to 107 milligrammes. Other kinds
of wax and its substitutes require in some cases more and in others
less of the alkali. This method would, however, lead to very erroneous
conclusions if applied to a mixture of which some of the constituents
have higher saponification numbers than beeswax and others higher, as
one error would balance the other.
To avoid this, the quantity of alkali required to saponify the
myricine is first ascertained, and then that required to saturate the
free cerotic acid. In this way two numbers are obtained; and in an
investigation of twenty samples of Austrian yellow beeswax, the author
found these numbers stood to each other almost in the constant ratio
of 1 to 3.70. Although this ratio cannot be considered as definitely
established by so few experiments, it may serve as a guide in judging
of the purity of beeswax.
The experiment is carried out as follows: 3 or 4 grammes of the wax
that has been melted in water are put in 20 c.c. of neutral 95 per
cent, alcohol, and warmed until the wax melts, when phenolphthaleine
is added, and enough of an alcoholic solution of potash run in from a
burette until on shaking it retains a faint but permanent red color.
The burette used by the author is divided in 0.05 c.c. After adding 20
c.c. more of a half normal potash solution, it is heated on a water
bath for ¾ hour. Then the uncombined excess of alkali is titrated with
half normal hydrochloric acid. The alcohol must be tested as to its
reaction before using it, and carefully neutralized with the acid of
phenolphthalein.
To saturate the free acid in 1 gramme of wax requires 19 to 21
milligrammes of potassic hydrate, while 73 to 76 milligrammes more are
necessary to saponify the myricine ether. The lower numbers in the one
usually occur with low numbers for the other, so that the proportions
remain 1 to 3.6 or 1 to 3.8.
For comparison he gives the following numbers obtained with one gramme
of the more common adulterants:
----------------+----------+----------+---------+--------+
| To | To | Total | |
|neutralize| convert |saponifi-| |
| the acid.|the ether.| cation. | Ratio. |
----------------+----------+----------+---------+--------+
Japanese wax | 20 | 200 | 220 | 10 |
Carnauba wax | 4 | 75 | 79 | 19 |
Tallow | 4 | 176 | 180 | 44 |
Stearic acid | 195 | 0 | 195 | 0/195 |
Rosin | 110 | 1.6 | 112 | 0.015 |
Paraffine | 0 | 0 | 0 | 0 |
Ceresine | 0 | 0 | 0 | 0 |
Yellow beeswax | 20 | 75 | 95 | 3.75 |
----------------+----------+----------+---------+--------+
The author deduces the following conclusions as the results of these
investigations:
1. If the numbers obtained lie between these limits, 19 to 21, 73 to
76, 92 to 97, and 3.6 to 3.8 respectively, it may be assumed that the
beeswax is pure, provided it also corresponds to beeswax in its
physical properties.
2. If the saponification figures fall below 92 and yet the ratio is
correct, it is adulterated with some neutral substance like paraffine.
3. If the ratio is above 3.8, it is very probable that Japanese or
carnauba wax or grease has been added.
4. If the ratio falls below 3.6, stearic acid or resin has been used
as the adulterant.
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