278 MR. H. GRIMSHAW ON BASIC CALCIUM CHLORIDE. 



graphic image which is nearly latent, and which may be 

 developed by the ordinary ferrous developer used in pho- 

 tography. To produce this image, two or three minutes' 

 exposure to sunlight is required. To develop it, it is es- 

 sential that little or no silver nitrate be present ; otherwise 

 the exposed and unexposed parts are reduced indiscrimi- 

 nately. 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. 



XXXVII. On Basic Calcium Chloride. 

 By Harry Grimshaw, F.C.S. 



Read November 17th, 1874. 



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 chlo- 

 ride of calcium and lime, or hydrated tetra-hydrochlorate 

 of lime, and, according to him, has been noticed byBucholtz 

 and Frommsdorf and by Berthollet, and analyzed by H. 

 Rose, who found the formula 3 CaO, CaCl+ 16 Aq, or, in 

 present notation, 3 CaO, CaCl z + 16 H 2 0. This is not a 

 very simple or intelligible formula ; and moreover the per- 

 centage of water found, which was 49*084, is considerably 

 lower than that required by the formula, namely 50793. 

 The salt was therefore prepared and analyzed as follows. 



The solution of calcium chloride was prepared by dis- 

 solving, by heat, pure white marble in moderately concen- 



