Contributions to Experimental Chemistry, 373 



. When the calcareous salts amounted to 5 per cent, of the 

 magnesian salts, oxalate of lime was instantly precipitated ; but 

 its quantity, after 24 hours, was only to be estimated at about 

 •I- of that which would have been precipitated without the pre- 

 sence of the magnesian salts. 



AVith 2 per cent, of the calcareous salts, the precipitation of 

 the oxalate of lime began after some minutes ; and after 24 

 hours, the quantity of it appeared to be no more than about 

 •^ of that to be indicated by the re-agent. 



With 1 per cent, there was nothing precipitated during the 

 first hour, and the precipitate was very inconsiderable, even 

 after 24 hours, especially in the solutions of muriate of lime 

 and magnesia. Similar results were obtained when the salt of 

 lime was ^^j or -^^ of the magnesian salt ; and the whole weight 

 of the solution amounted to 500 times the weight of the former. 



The precipitates produced by oxalate of potash, were almost 

 always more copious than those by oxalate of ammonia — a fact 

 which has already been observed by M, Du Menil, who found 

 the quantity of the precipitate by the former, to be to that by 

 the latter, as 22.0 to 22.5. 



The following experiments prove the analysis, by dissolving 

 the sulphates in a solution of sulphate of lime, to give a more 

 satisfactory result. 



A solution, containing 0.4 grain of sulphate of lime, and 40 

 grains of sulphate of magnesia, was evaporated. The remain- 

 der being heated to redness, and dissolved in 300 grains of a 

 solution of sulphate of lime (containing 0.002 of the sulphate) 

 at the common temperature, left sulphate of lime, which was 

 collected on a filter weighing 6.85 grains, and washed eight 

 times with 100 grains of the solution of sulphate of lime. Hav- 

 ing passed completely through the filter, the latter was put, 

 in a wet state, into a platinum crucible. Its weight was found 

 to be 27.2 grains, and after calcination, 0.5 grain of ashes re- 

 mained. Now, as the filtering paper employed was known to 

 leave 0.32 per cent, of ashes, the quantity of the sulphate of 

 lime separated from the magnesian salt, will be equal to 

 0.5 -(27.2X0.002 + 6.85X0.0012) ^ ^ ^^^ .^^ 

 0.998 * 



This quantity is 0.038 grains more than it ought to be ; but 



