JQ2 ANALYSIS OF BRITISH AND FOREIGN* SALT. 



"however, exposed daring equal times to a low red heat, do 

 not lose more than from half a grain to three grains in one 

 hundred. This comparison cannot be extended to the salt 

 *':• ^ prepared at a boiling temperature from seawater; became 



the muriate of magnesia, which these varieties contain, is 

 decomposed at a red heat, and deprived of its acid. 



The following table shows the quantity of water contained 

 in several kinds of salt, inferred from the loss which they 

 sustain by ignition during equal times, after being first diiad 

 at 212°. 



Froportwnje of 100 parts of large grained fishery salt contain of water 3 



tbi* wai«. 100 foreign bay salt (St. Martin's) 3 



IOO ditto (Oleron) ,. fcf 



100 ditto Cheshire common salt ]J 



100 '•..••» ditto stoved salt Of 



The loudness and violence of the decrepitation was, as 

 nearly as could be judged, in the same order, and was most 

 remarkable in the large grained varieties. 

 Proportion? of t determine the proportions of real muriate of soda in 

 given by on rate, those varieties of artificial salt which are nearly free from 

 of silver. earthy muriates, 1 employed also the process of decompo- 



sition by nitrate of silver. The following are the quantities 

 of fused luna cornea, obtained from 100 grains of each of 

 three varieties dried, previously to solution, at the tempera-- 

 ture of 212° Fahrenheit. 



100 gr. pure transparent rock salt gave of luna cornea 242 



J 00 • • stoved salt, remarkably pure 239 



100 • • fishery salt, ditto 237* 



* From too grains of pure artificial muriate of soda, previously 

 heated to redness, Dr. Marcet has since informed me, that he obtained 

 24 1 "6 grains of fused luna cornea. The weights of the precipitates 

 thrown down in my experiments by nitrate of silver are not, I am aware, 

 exactly those which might have been expected from the table of the 

 comparative, proportions of water given in the text. Each experiment, 

 however, was twice repeated with every nr cannon I could adopt, and 

 with the same results. That different, kinds of salt fifive different pro- 

 portions of luna cornea, is proved also by comparing the experiment of 

 pr. Marcel with the results of Dr. Black and Klaproth, both of whom 

 found ibe fused muriate of silver, from loo parts of common salt, to 

 weigh 235 graias. 



The 



