REPORT ON CHEMISTRY. 
521 
its weight. Concentrated acids and alkalies, even at a boiling 
temperature, do not decompose it. 
This remarkable substance is recommended, by its great ex¬ 
pansibility and high boiling point, as a fluid likely to be useful 
in the construction of thermometers. Its power of resisting the 
action of all chemical reagents may render it, as is remarked by 
Berzelius, applicable in many cases as a solvent. He draws at¬ 
tention also to the liquid found by Sir David Brewster in the 
cavities of the topaz, to the highly expansive power of which 
this new fluid presents an approximation*. 
Organic ?natter in mineral waters .—The slime deposited in 
the bath of Tatenhausen has lately been examined by Brandes, 
and found to contain an organic substance in combination with 
the peroxide of iron. The slime is treated with caustic potash 
or ammonia, the solution decanted, saturated with acetic acid 
and evaporated to dryness. Alcohol separates the acetate and 
leaves the organic matter. It constitutes a dark brown gummy- 
like mass, which is tasteless, soluble in water, and contains azote. 
It exists in the water when it issues from the spring, and is pre¬ 
cipitated with the iron on the latter attracting oxygen from the 
air and becoming peroxidized. 
Berzelius has recently commenced an examination of a mineral 
water found atPorla in Sweden, in which an oclireous precipitate 
is formed, and has found in it a similar organic principle, which 
may be separated by the process above described. He has found 
it to possess decidedly acid properties ; and the probability is 
that it exists in the water in the state of an acid holding iron in 
solution, with the protoxide of which it forms a soluble, and with 
the peroxide an insoluble compound. This is supported by the 
fact that if the insoluble sediment be mixed with water, and sub¬ 
jected to a current of sulphuretted hydrogen, the iron does not 
fall in the state of sulphuret, but is retained in solution by the 
acid. To the publication of Berzelius’s results we may look for 
much information on this curious subject. 
Organic matters of this kind have been met with in several 
instances in springs which, like those above mentioned, issue 
from primitive rocks. What can be the origin of the organic 
matter which such geological formations afford ? 
Section II .—Animal Principles and Products. 
The number of proximate animal principles yet known is very 
small compared with those discovered in the vegetable kingdom. 
Animal chemistry has chiefly been studied in connexion with 
* Arsbercittelse, 1832, p. 320. 
