INORGANIC COMPOUNDS. 79 
other parts, being taken in with the f I.' and no! excreted at once with the 
faeces, but deposited in some tissue or organ. Drugs ami poisons (mercury, 
arsenic) may be similarly deposited. 
Silica. — A minute quantity of silica exists in the blood, urine, bones, 
hair, and other parts. 
Phosphates. — The amount of phosphoric acid given in analyses of 
the ash of animal structures is not always correct, since a certain 
quantity is obtained during the process of incineration, from the decom- 
position of organic compounds, which, like lecithin, contain phosphorus. 
The phosphoric acid which occurs in mineral compounds in the body 
is derived in part directly from the food, and in part from the metabolism 
of lecithin and nuclein. It unites with soda, potash, lime, and magnesia 
to form the various phosphates already alluded to. An adult man 
eliminates by the kidneys 2'5 to 3"5 grms. of phosphoric acid daily. 
Carnivora eliminate phosphates chiefly by the kidneys, herbivora chiefly 
with the faeces. 
Carbonates. — The presence of carbonates in the ash of animal matters 
is partly derived from the decomposition of organic compounds. 
Alkaline carbonates and bicarbonates are, however, found in blood, 
urine, lymph, saliva, etc 
Sulphates. — These also maybe partly formed during the process of 
incineration, from proteids and other organic compounds containing 
sulphur. The sulphuric acid in the urine is in part combined as ordinary 
sulphates, in part as ethereal sulphates. It is derived to a small extent 
from the food, but chiefly from the metabolism of proteids, the amounts 
of sulphuric acid and urea in the mine running parallel. 
1 Karl B. Lehmann {Arch. f. Hyg., Miinchen u. Leipzig, Bd. xxiv. S. 1, 18, 72) 
states that in an ordinary diet we take 20 mgrms. of copper daily, and if preserves are much 
used, it may rise to over 300 mgrms. per diem ; more than 120 mgrms. appears to be harmful. 
