20 Di:. Ure on Chloride of Lime. 



of vinegar, carbonic acid gas may supply its place. A large 

 glass flask being filled with this gaseous acid, 20 or 50 grains 

 of bleaching-powder may be introduced, and well agitated in 

 the gas, 10 grains of lime take 17.2 cubic inches of carbonic 

 acid, equal to 8 grains in weight. Therefore if 20 grains of 

 lime, be present in 50 grains of the chloride-part of the bleach- 

 ing-powder, (exclusive of muriate,) they will require 86 cubic 

 inches, or three wine pint measures of carbonic acid gas. Or 

 it will be equally convenient to immerse in the powder, diflfused 

 through a little water, a glass tube, discliarging carbonic acid 

 gas, from a flask containing chalk, and dilute sulphuric acid. 

 If the bleaching-powder and water, be kept slightly warm in a 

 little glass globe, into which the gas-tube is dipped, then the 

 instant when the chloride is decomposed, and the lime carbo- 

 nated, will be found by the liquid ceasing to make any perma- 

 nent change on litmus paper. The muriate of lime is with- 

 drawn by solution in water. The weight of calcareous carbo- 

 nate must then be compared with that of the chlorine disen- 

 gaged, from another equal portion of the powder, by dilute 

 muriatic acid. Finally, the water may be found by distillation 

 in a retort. Thus the analysis will be completed, with little 

 manipulation and no fallacy *. For the purpose of commerce 



* I have found on trial, the method by carbonic acid, to be exceedingly 

 slow and unsatisfactory. After passing' a current of this gas for a whole 

 day through the chloride diffused in tepid water, I found the liquid still to 

 possess the power of discharging the colour very readily from litmus 

 paper. But the doctrine of equivalents furnishes a very elegant theorem 

 with acetic acid, whose convenience and accuracy in application I have 

 verified by experiment. Au a])parently complex, and very important 

 problem, of practical chemistry is thus brought within the reach of the 

 ordinary manufacturer. Since common fermented vinegar, is permitted 

 by law to contain a portion of sulphuric acid, which avarice often leads 

 the retailer to increase, we cannot employ it in the present research. But 

 strong vinegar prepared from pyroligneous acid, such as that with which 

 Messrs. TurnbuU and Ramsay have long supplied the London market, 

 being entirely free from sulphuric acid, is well adapted to our purpose. 

 With such acid contahied in a poised phial, fully saturate a given weight, 

 (say 100 grains,) of the bleaching-powder, contained in a small glass 

 matrass, applying a gentle heat at last, with inclination of the mouth of 

 the vessel, to expel the adhering chlorine. Note the loss of weight due to 

 the disengagement of the gas. (If carbonic acid be suspected to be 



