58 Improvements in Physical Science [Jaw. 
Islands by the hirwndo esculenta, which are in such high request in 
China as an article of luxury, have been lately subjected toa che- 
mical analysis by Dobereiner. He found them composed of the 
following constituents : 
Mucus. greatest part of the nest is 
Albumen. composed. It swells, becomes 
A trace of gelatine. transparent and gelatinous like 
A peculiar substance, insoluble tragacanth, when boiled or 
in water, alcohol, and most digested in water. 
other reagents, bearing some | Common salt. 
resemblance to fibrin; but | Soda, 
constituting in fact a distinct | Lime. 
animal body. Of this the | lron. 
13. Fat Bodies.—Chevreul has been employed for several years 
in ascertaining the effects produced by alkalies upon tallow, hog’s 
lard, or other fatty bodies, and in endeavouring to form a theory 
of saponification. . During the course of the last year he has pub- 
lished no fewer than four dissertations upon this subject. Oils and 
tallow he finds do not uniteas such to alkalies. They are decom- 
posed into three new substances to which he has given the name of 
margarine, fluid fat, and sweet principle. The first is solid, and 
received its name from its resemblance in colour to pearl; the 
second and third are liquid. The first two of these bodies unite 
with alkalies, and form soap; the third separates altogether. These 
new substances are formed without the evolution of any gas, or 
the absorption of any oxygen from the atmosphere. Chevreul con- 
siders margarine and fluid fat as substances possessing acid pro- 
perties, and therefore capable of combining with and neutralizing 
the salifiable bases. ‘The compounds thus formed are called soaps, 
or plasters, according to the uses to which they are applied. The 
following are the constituents of the soaps of margarine, according 
to the experiments of this chemist : 
Margarate of Potash. Margarate of Strontian. 
Margarine ...... 100 Margarine ....... 100 
oe Koel, Rep eye end and | Strontian........ 20°23 
argarine ...... ; 
Fag) ee a 17°77 Margarate of Lime. 
Margarine ....... 100 
OTERO sod Lime sto) See ae 
Margarine ....... 100 
Soday palma: 9 1272 and|  - Margarate of Lead. 
Margarine ....... 100 Margarine ....... 100 
Soda ...... wee eees 5°93 Yellow oxide of lead 83°78 and 
Margarate of Barytes. Margarine....... 100 
Margarine .:..... 100 Oxide of lead.... 41°73 
Barytes: 0: 20s 5 oa '2B:93 
Chevreul gives also the composition of the soaps of liquid fat ; 
but for these I must refer the reader to the memoir itself, published 
in the 94th volume of the Annales de Chimie, p. 263. 
3 
