48 
paper be kept for some weeks its colour changes to that of 
a yellowish brown, free vanadic ‘ acid appearing to be 
produced. 
Gelatine impregnated with sodium ortho vanadate exposed 
to light, and afterwards dipped into a solution of silver 
nitrate, becomes insoluble in hot water. 
Silver orthovanadate is capable of forming a photographic 
image, which is nearly latent, and which may be developed 
by the ordinary ferrous developer used in photography. 
To produce this image two or three minutes’ exposure to 
sunlight is required. To develope it, it is essential that 
little or no silver nitrate be present ; otherwise, the exposed 
and unexposed parts are reduced indiscriminately. The 
washed silver vanadate can be mixed with a solution of 
gelatine containing a little albumen, spread upon paper, and 
allowed to dry ; it can then be exposed to light, and 
afterwards developed. 
“On Basic Calcium Chloride,” by Harey Geimshaw^ 
F.C.S. 
When a strong solution of calcium chloride is boiled with 
calcium hydrate, the solution filtered, and allowed to cool, a 
salt separates out in long, slender, needle-shaped crystals. 
This salt is called in Gmelin’s Handbook, hydrated chloride 
of calcium and lime, or hydrated tetra-hydrochlorate of 
lime, and, according to him, has been noticed by Bucholfcz 
and Trommsdorf and by Berthollet, and analysed by H. 
Bose, who found the formula SCaO, CaCl+16Aq, or in pre- 
sent notation SCaO, CaCl2+16H20. This is not a very 
simple or intelligible formula, and moreover the percentage 
of water found, which was 49 '084, is considerably lower 
than that required by the formula, namely, 50'793i The 
salt was therefore prepared and analysed as follows. 
The solution of calcium chloride was prepared by dissolv- 
ing, by heat, pure white marble in moderately concentrated 
hydrochloric acid until saturated. This was boiled with an 
