OF ARTS AND SCIENCES. 59 



Neuhof obtained a similar salt, but describes it as more soluble in 

 water than ours. 



We did not succeed in getting a pure, well-defined calcic salt, al- 

 though we tried to do so several times. By adding lime-water to the 

 acid till the reaction was alkaline, removing the excess of lime by 

 carbonic dioxide, and allowing the solution to evaporate spontaneously, 

 arborescent groups of white needles were obtained. These lost 9.84 

 per cent when dried at 100° ; 2 molecules of crystal water would 

 give 8.68 per cent; 2\ molecules, 10.61 per cent; the loss, there- 

 fore, does not correspond to any probable amount of water of crys- 

 tallization, and it seemed likely that something beside water was given 

 off, as there was a slight sublimate on the upper watch-glass, and the 

 substance had become somewhat brown, with a semifused look very 

 unlike its original appearance. It, however, contained 10.36 per cent 

 of calcium, and may therefore have been the anhydrous salt which 

 needs 10.55 per cent. Other experiments under different conditions 

 gave no better results, and we therefore decided that the salt was not 

 important enough to repay a thorough study, which would use up a 

 great deal of time. 



The baric salt was even less well defined than the calcic: it was 

 prepared in the same way, and appeared on evaporation of its solution 

 over sulphuric acid as a colorless varnish, part of which changed on 

 stirring into a radiated crystalline mass. This became white and 

 opaque when treated with cold water, and when boiled with water 

 gave an acid reaction and the smell of the acid. If the solution was 

 evaporated on the water-bath instead of over sulphuric acid, a sticky 

 gum was left. Neuhof's baric salt was similar to ours, and gave him 

 an amount of barium corresponding to an acid salt. His calcic salt, 

 on the other hand, contained one molecule of water, which it lost 

 at 100°. 



A solution of the acid in ammonic hydrate, from which the excess 

 of ammonia has been driven off on the water-bath, gives reactions 

 with salts of the various metals similar to those of the corresponding 

 brom-acid.* The bluish-green flocks with cupric sulphate, yellowish- 

 brown with ferric chloride, and white with plumbic acetate or mercurous 

 nitrate are especially characteristic. 



Parachlorbenzylsulphocyanate, O e H i CI GH t SCN, made by boiling the 

 bromide with an alcoholic solution of potassic sulphocyanate, was 

 purified by freezing with snow and salt, sucking out the oil with filter- 



* These Proceedings, XII. (n. s. IV.) p. 225. 



