102 HOW CROPS GROW. 
from which it is very difficult to separate them fully. 
Again, if we succeed in removing foreign substances, it 
must usually be done by the aid of acids, alkalies, and 
other strong reagents, which easily alter or destroy their 
proper characters and composition. Finally, if we analyze 
the pure substances, our methods of analysis are perhaps 
scarcely delicate enough to indicate their differences with 
entire accuracy. 
The results of chemical investigation demonstrate that 
the albuminoids are either identical in composition or 
differ but slightly from each other, as is seen from the 
Table below. The deduction of a correct atomic formula 
from these analyses is perhaps impossible in the present 
state of our knowledge. 
In the subjoined Table are given analyses of the albuminoids 
which have been described: Those indicated by asterisks are recent re- 
sults of Dr. Ritthausen; the others are average statements of the best 
analyses, (after Gorup-Besanez, Org. Chemie, p. 611.) 
COMPOSITION OF ALBUMINOIDS. 
al 
Carbon. Hydrogen. Nitrogen. Oxygen. Sulphur. 
Animal albumin...... 53.5 7.0 15.5 22.4 1.6 
Vegetable albumin... .53.4 “1 15.6 23.0 0.9 
Blood fibrin.......... 52.6 7.0 17.4 21.8 1.2 
Flesh fibrin...........541 13 16.0 21.5 11 
Wheat fibrin*........ 54.3 V2. 16.9 20.6 1.0 
Animal casein........ 53.6 1 15.7 22.6 1.0 
Vegetable casein...... 50.5 6.8 18.0 24.2 0.5 
Gluten-casein*) .......51.0 6.7 16,1 25.4 0.8 
Gliadin* wheat 52.6 7.0 18.1 21.5" 0.8 
- Mucedin* J vee SAL 6.9 16.6 21.5 0.9 
Phosphorus is not included in the above table, for the reason that in 
all cases its quantity, and in most instances its very presence, is still un- 
certain. Voelckerand Norton found in vegetable casein 1.4 to 2.3 per 
cent of phosphorus, and smaller, quantities have been mentioned by 
other of the older analysts as occurring in albumin and fibrin. The 
phosphorus of these and of animal casein is thought not to belong to 
the albuminoid, but to be due to an admixture of phosphate of lime. 
In his recent investigation of gluten-cascin, Ritthausen found phos- 
phoric acid that appears to have been partially uncombined with a fixed 
base, and to have therefore resulted from phosphorus in organic combi-+ 
