18 On the Oxymuriate of Lime, [Jan^ 



pbate IS deficientj a strong smell of bxymuriatic acid accom- 

 panies the mixture ; whence more sulphare must be added, till 

 the mixture, on due agitation, ceases to emit the fumes of the oxy- 

 muriatic acid : if too much sulphate is put in, then more of the 

 acid liquor must be added by degrees, till its peculiar odour is 

 developed. A very few drops of either liquor are sufficient to 

 give the mixture a character when near the point of saturation. 

 I found that 40 grain measures of a solution of sulphate of iron 

 of the sp. gr. 1'149 were sufficient to saturate 100 measures of 

 oxymuriate of lime of 1*034 sp. gr. — In order to understand 

 more clearly the relative weights of oxy muriatic, acid and oxide of 

 iron, which are required for mutual saturation, I made the fol- 

 lowing .experiment. 



ExPER. IV. — A graduated tube was filled with oxymuriatic 

 acid gas. This was then plunged into a dilute solution of green 

 sulphate of iron, and the whole of the gas was by due agitation 

 immediately absorbed by the liquid. If any smell of oxymuriatic 

 acid remained, the experiment was repeated on a stronger solu- 

 tion of green sulphate ; but if no smell remained, then it was re- 

 peated with a weaker solution ; till in a few trials the strength 

 of the sulphate was found, which was just sufficient to cover the 

 smell of the gas ; or in other words, to saturate the acid. This 

 was when the solution was of TO 120 sp. gr. or nearly -^-^ of the 

 strength which I commonly use as a test solution, as mentioned 

 above. Now 100 measures of oxymuriatic acid gas weigh -29 of 

 a grain, reckoning its specific gravity at 2-46; and 100 measures 

 of the sulphate contain (as I find by experience) 1*32 grain of 

 real dry salt, of which GS parts are sulphuric acid, and 64 parts 

 oxide of iron; of which 50 are iron, and 14 oxygen, as is well 

 known. The red oxide of iron is known to contain half as much 

 more oxygen as the black ; hence 64 parts of black oxide will 

 become 7 1 of red, or the blatk oxide receives 7 parts of oxygen 

 from the 29 of oxymuriatic acid, and reduces it to 22 of muriatic 

 acid. These numbers perfectly accord with those deduced as 

 the weights of the respective atoms in the 2d part of my che- 

 mistry. — We are npw enabled to find the quantity of oxymuriatic 

 acid in the 1*034 oxymuriate of lime. As 100 measures require 

 40 of 1*149 sulphate of iron, and these contain 3*2 grains of 

 black oxide ; we shall have 64 : 29 :: 3*2 : 1*45 grain, for the 

 weight of oxymuriatic acid in 100 measures of liquid oxmuriate 

 ©f lime of the sp. gr. 1*034. This is five times the volume of 

 tlie liquid in gas. 



In 100 measures of the solution of oxymuriate of lime of 

 1^034 we therefore find, 



\'¥h Lime. 

 *C)5 Muriatic acid. 



1*45 Oxymuriatic acid. 



3-95 



