300 Apparatus for Analyzing Calcareous Marl, &fc. 



From the construction of Rose's instrument its weight must always 

 be so great as to render an exact estimation of the carbonic acid im- 

 possible by means of any but the most accurate and expensive bal- 

 ances. Besides which I have found the contrivance for bringing the 

 acid and carbonate together very difficult to regulate and liable to 

 accidents which often make it necessary to repeat the analysis. 



From the subjoined figure and description it will be evident that 

 the apparatus here recommended is free irom these objections. The 

 accuracy of its results and the facility with which it may be used in 

 the analysis of marl and the carbonates generally, will I think entitle 

 it to the notice of the practical chemist. 



The balance I employ with this apparatus is of the kind sometimes 

 used by goldsmiths, having a light beam, and turning readily when 

 unloaded with 3 1 ^ of a grain. This is accompanied by a set of 

 weights extending to tenths and hundredths of the grain. One of 

 tire scales- is r enio ved- to admit of suspending the apparatus by a 

 double thread over the hook of the beam. The other is made of 

 something light, as a piece of card, or which is better, a thin sheet 

 of mica. In this way all unnecessary weight upon the beam is 

 avoided and its sensibility preserved. 



A is a light bulb of glass, blown very thin from a piece of tube, 

 and about one inch in diameter. A cork is fitted to its mouth, and 

 through this the tapered ends of the bent glass tubes B and C are 

 passed air tight, the extremity of the latter extending some distance 

 into the vessel. The tube B through which the gas escapes is filled 

 with fragments of muriate of lime or with dry carded cotton. If 



