Mr. Taylor on the Solubility of Arse?iious Acid. 485 



Twenty-five grains of the cold solution, evaporated, left *55 gr., rather 

 less than the proportion deduced from the weight of the undissolved 

 residue. 



" Exp. 5. In this experiment four ounces of water were kept vio- 

 lently boiling for half an hour ; arsenious acid being added, as before, 

 from a weighed quantity. 89 gr. were dissolved. Hence, 



1 000 gr. water dissolved (89-*- 2) . . . 44 5 gr. or about £?. 

 The mean of Exps. 3, 4, and 5, will be the following : 



1000 gr. of boiling water dissolve .... 40*76 gr. or -yV* 

 The rapidity of boiling will make a considerable difference in the quan- 

 tity dissolved, as will be seen on comparing Exps. 3 and 4. Indeed, 

 water which boils violently will dissolve as much arsenic in half an 

 hour as water kept gently boiling will dissolve in an hour. All other 

 circumstances being equal, the length of time during which the boiling 

 continues will assuredly make a difference in the quantity of the poison 

 taken up. 



" Exp. 6. Arsenious acid, in fine powder, was boiled for several 

 hours to saturation, in two separate quantities of water. These solu- 

 tions were, after filtration, kept apart j and allowed to stand for six 

 months in well-stoppered bottles. A very abundant crop of oetohe- 

 dral crystals, lining the whole interior of the bottle, was deposited in 

 each case. After this lapse of time, twenty-five grains of the filtered 

 solution (A) were evaporated to dryness $ and the solid residue weighed 

 *7 grain. Hence, 



1000 gr. of the solution contained 40 x *7=28" gr. or &.. 

 Twenty-five grains of (B) left, as a solid residue, *6 gr. Hence, 



1000 gr. held dissolved 40 X *6=24 gr. or nearly ^. 

 The mean of these two experiments will be as follows : 



1000 gr. of a saturated solution, after six months' standing, held 

 dissolved 26 gr. or -j-g. 



" In closing these remarks on the solubility of arsenic in boiling 

 water, I shall subjoin the results of some experiments on the recently- 

 prepared, or transparent, arsenious acid : and I am the more desirous 

 of doing this, since the statements of Guibourt, relative to the trans- 

 parent being less soluble than the opaque variety, are not supported 

 by them. In a medico-legal point of view, the question of a differ- 

 ence of solubility in these varieties of arsenious acid is not, perhaps, 

 of much importance ; since the pure transparent arsenic is with dif- 

 ficulty obtainable, and is rarely sold by druggists. 



'* Exp. 7. A perfectly transparent and recently-prepared mass of 

 arsenious acid was finely pulverized j and a weighed quantity of the 

 powder was gradually added to two fluid ounces of water, kept violently 

 boiling for an hour, the waste by evaporation being made up. Forty- 

 six grains were dissolved. 



1000 gr. water dissolved .... 46 gr. or nearly -5V. 



From this solution there were deposited in crystals, after 48 hours, 

 27-3 gr. and 46—27*3= 187. 

 1000 gr. water held dissolved, on perfect cooling .... 18*7 gr. or ^v. 

 " Exp. 8. In this experiment four ounces of water were kept boil- 



