Analytical Process.

The weighed cadmium chloride was dissolved by placing the boat containing it in an Erlenmeyer flask containing water. The boat was then washed, dried and replaced in its weighing-tube. On weighing again, the loss in weight is equal to the weight of cadmium chloride taken. All samples gave a perfectly clear solution except those used for determinations XX and XXI. A drop of nitric acid (1:3) was added to each solution except in determination XIV where the cubic centimetres were added, and in XVI where ten cubic centimeters were added. A solution of silver nitrate was then added to precipitate the chlorine. This as well as the subsequent washing was done in a dark-room illuminated by a single gas light whose rays had to pass through a strong solution of neutral potassium chromate. The precipitate was contracted by warming on the water-bath. It was then collected in the prepared Gooch crucibles and washed. Before filtering, the flask containing the precipitate and mother-liquor was allowed to cool. Silver chloride is soluble in water to a considerable extent but is reprecipitated by adding an excess of either silver nitrate or hydrochloric acid. Stas (Ann. de Chem. et Phys. [4], 25, 22; [5], 3, 145; [5], 3, 289.) investigated this very thoroughly. Cooke also did some work on it and used a dilute solution of silver nitrate to wash the chloride thus preventing solution (Proc. Amer. Acad. 17, 7.). In the above work, therefore, a solution containing 0.10 grammes of silver nitrate per liter was first used, followed by one only one-tenth as strong, and finally pure water was used. Only two or three washings could be made with water as the chloride went into solution after this owing to the removal of the silver nitrate. The last silver nitrate solution used is so weak that any error introduced by not washing it out completely is insignificant. After washing, the silver chloride was dried at temperatures varying from 150°C. to 300°C. to constant weight. A glass air-bath was used in order to prevent products from the burning gas from coming in contact with the chloride. It was then weighed. The quantity of silver nitrate used in the determinations was varied very much. The excess over what was required to precipitate the chloride is given in the table of results in those cases in which it is known. The quantity of water used in each determination is also given where it is known. It is given in the number of cubic centimetres used per gramme of cadmium chloride and does not include wash water. All weighings are reduced to the vacuum standard on the basis that Sp. Grs. of CdCl₂ = 3.94 and AgCl = 5.5. The results are:

No.	CdCl₂	AgCl	H₂O per Grm.	Excess AgNO₃	At. Wt.	Melted in

I	3.09183	4.83856			112.339	Dry HCl
II	2.26100	3.53854			112.329	„ „
III	1.35729	2.12431			112.320	Moist HCl
IV	2.05582	3.21727			112.339	„ „
V	1.89774	2.97041			112.306	„ „
VI	3.50367	5.48473		8.90	112.283	„ „
VII	2.70292	4.23087	200	1.79	112.301	„ „
VIII	4.24276	6.6398	300	8.10	112.387	„ „
IX	3.40200	5.32314	300	18.95	112.368	„ „
X	4.60659	7.20386	300	25.62	112.472	„ „
XI	2.40832				112.434	Dry HCl
XII	2.19114	3.42724			112.433	„ „
XIII	2.84628	4.45477	300	4.45 + 3cc. HNO₃	112.319	„ „
XIV	2.56748	4.01651	300	.10	112.399	„ „
XV	2.31003	3.61370	300	.10 + 10cc. HNO₃	112.406	„ „
XVI	1.25008	1.95652	300	4.66	112.319	„ „
XVII	1.96015	3.06541	300	3.22	112.466	„ „
XVIII	2.29787	3.59391	300	4.27	112.448	„ „
XIX	1.94227	3.03811	300	3.61	112.423	Dry HCl
XX	1.10976	1.73547			112.471	„ „
XXI	1.63080	2.55016			112.476	„ „

				Average	112.383