222 J. P. Cooke on the Law of Definite Proportions 
For the determination of nitrogen I do not use the bicarbonate 
of soda but the following apparatus, from which a current of car- 
bonic acid is passed through the combustion tube. 
& 
A is a Woulfe’s bottle containing diluted muriatic acid. 
B, a similar bottle with pieces of chalk and water. 
C, Chlorid of calcium tube, part of it filled with chalk; a piece or two of pumice 
stone separates the two substances. 
, Combustion tube. 
Condensing the air in bottle A by blowing through the mouth- 
piece a, some of the acid passes into B and sets carbonic acid free, 
cock could be omitted, but the little expense hardly justifies such 
a simplification. 
SS SS 
+ 
Art. XXII.—On an apparent Perturbation of the Law of Defin- 
ite Proportions observed in the Compounds of Zine and Anti- 
mony ; by Jostan P. Cooke, Jr., Cambridge.*—With a plate. 
Ix a former paper in this Journalt I described two new com- 
pounds of zinc and antimony Sb Zns and Sb Zn which I named 
respectively, Stibiotrizincyle and Stibiobizincyle, because they te- 
semble in their composition the metallic radicals of organic chem- 
istry, and because the first decomposes water rapidly at 100°C. 
I there stated that crystals of Sb Zns could be obtained contail- 
ing a much larger amount of zinc than that required by the law” 
* Abstract from a Memoir of the American Academy, New Series, vol. v, p- 337 
+ This Journal, vol. xviii, p. 234. : 
