1813.] 



On the Oxymuriate of Lime. 



15 



Cavendish's last astronomical paper^ and the last paper which he 

 ever published, is an account of a set of experiments made to 

 determine the density of the earth by rendering sensible the 

 attraction of small quantities of matter. (Phil. Trans. 17^8, 

 vol. Ixxxviii. p. 469.) The apparatus v^^as originally contrived by 

 Mr. John Mitchel; but was new modelled, and greatly im- 

 proved, by Mr. Cavendish. The result of these experiments 

 was, that the mean density of the earth does not diiFer from 

 5*48 by so much as -V^^^ of the wholes that is, that it is not less 

 than 5*09, nor greater than 5*87. The experiments of Dr. 

 Maskelyne on Schehallion, when corrected by the late observa- 

 tions of Mr. Playfair, give the density of tbe earth 4'867. 

 These two sets of observations compared, would induce one to 

 suspect that the mean density of the eartli does not differ muck 

 from 5. 



Article II. 



On the Oxymuriate of Lime, By Mr. John Dalton. 



The article called oxymuriate of lime is of great importance 

 to the manufactures, it being used largely in the bleaching of 

 cotton and linen goods. It would also be of great use to the 

 practical chemist, were its properties generally known. As no 

 book of chemistry that I am acquainted with does any tbing more 

 than just mention the article, and as it has lately fallen in my 

 way to investigate its constitution and properties, 1 thought it 

 might be acceptable to several Members of the Society if the 

 results of my observations were niade the subject of a commu« 

 nication.* 



The oxymuriate of lime is exhibited in two forms ; namely^ 

 the fluid, and solid or dry form. In the first case it is made by 

 sending a current of oxymuriatic acid gas into a mixture of lime 

 and water ; the mixture is kept in a state of agitation during the 

 process, and the acid combines with the lime, forming with it a 

 compound soluble in water. In the second case, the oxymuriatic 

 acid gas is sent into a vessel containing dry hydrate of lime (that 

 is, lime slacked with the least possible quantity of water) ; the 

 powder is agitated, and the gas combines with it to a certain 

 amount, or till the hydrate of lime becomes saturated. The 

 compound is a soft white powder, possessing little smell. It is 

 partially soluble in water, yielding a solution much the same as 

 that obtained by the former process. 



Most salts that are soluble in water are capable of being 



* This essay was read at the Literary and Philosophical Sociciv, Manche:-- 

 terj Oct. 2, 1812. 



Q 



