276 



and by Pliny, as well as by Pococke, Volney, and other modern tra- 

 vellers, who all concur with respect to the intense saltness of the 

 water, which is such as to prevent either animals or vegetables from 

 living in it, a peculiarity from which it has derived its name. 



The only analysis which Dr. Marcet has been able to find recorded, 

 is that of Macquer, Lavoisier, and Sage, in the Mrm. de V Academic 

 for 1 778. But these chemists had not attained that accuracy of which 

 modern analysis is susceptible, and appear not to have bestowed upon 

 the subject that attention which is requisite in minute analytical ex- 

 periments. 



The quantity of the water of the Dead Sea, which was the subject 

 of Dr. Marcet's experiments, amounted only to about 1-| ounce ; but 

 it was in a phial, carefully corked, and appeared to be in a state of 

 perfect preservation. The smallness of the quantity, and difficulty 

 of obtaining a further supply, occasioned Dr. Marcet to be anxious 

 that none might be wasted in previous trials. He accordingly began 

 by a variety of comparative experiments on artificial solutions, in 

 order to ascertain the accuracy of various modes of operating ; and 

 as he knew by the analysis of Lavoisier and his associates, that the 

 principal ingredients which he might expect to find were the mu- 

 riates of soda, of magnesia, and of lime ; and as the general effect of 

 reagents tended to confirm their results, excepting that they indicated 

 the presence of a small quantity of selenite that had been overlooked, 

 the solutions on which Dr. Marcet's experiments were conducted 

 were made to consist of the same ingredients, and in proportions 

 which he previously ascertained with great precision. 



The first step, which appeared indispensable, was to determine the 

 proportions of acid and base in each of the three muriates. 



The composition of muriate of lime was ascertained by pouring a 

 quantity of muriatic acid on a piece of marble of known weight, and 

 larger than was necessary to saturate the acid : after saturation and 

 evaporation of the solution, the residuum was heated to redness, and 

 carefully weighed. From the weight of this residuum, after sub- 

 tracting the quantity of lime contained in a given weight of marble, 

 which, by a number of experiments performed jointly with Mr. Ten- 

 nant, was found to be 56*1 per cent., it appeared that 100 parts of 

 muriate of lime consist of 50'77 lime, and 49'23 muriatic acid. 



To discover the proportional parts of muriate of magnesia required 

 a synthetic process somewhat different. To a known weight of mag- 

 nesia previously calcined, was added such a quantity of muriatic acid 

 as would dissolve a known weight of marble ; and after the whole 

 of the magnesia had been dissolved, the excess of acid was saturated 

 with marble, by which the redundant quantity was ascertained. Hence 

 the quantity of acid combined with the given weight of magnesia was 

 deduced, and the component parts of muriate of magnesia determined 

 to be 43-99 magnesia, and 56'01 acid. 



The proportion of acid and alkali in muriate of soda, was found, 

 by various methods, to be 46 acid, and 54 soda. The best method 

 appeared to be that of precipitation by nitrate of silver ; the quan- 



