1823.] the same Crystalline Form as Pyroxene. 261 



pyroxene. The cleavage is very indistinct in the soft sahlites 

 which contain serpentine. Their external similarity only with 

 the hard sahlite, from Sahla, was the reason which induced M. 

 Rose to analyse them. It was necessary to repeat this analysis 

 often as it gave questionable results, until at last no doubt could 

 remain about their true chemical nature. The cleavages parallel 

 to the sides of the prisms and its truncations only were observ- 

 able, and very indistinct; the terminal face could not at all 

 be discerned. This imperfect crystalline structure depended 

 evidently upon the foreign admixture of serpentine. 



Article IV. 



Some Experiments and Researches on the Saline Contents of Sea- 

 water, undertaken with a View to correct and improve its 

 Chemical Analysis. By Alexander Marcet, MD. FRS. 

 Honorary Professor of Chemistry at Geneva.* 



In a paper on the temperature and saltness of various seas, 

 which the Ruyal Society did me the honour to publish in their 

 Transactions for the year 1819, I threw out a conjecture, that 

 the sea might contain minute quantities of every substance in 

 nature, which is soluble in water. For the ocean having com- 

 munication with every part of the earth through the rivers, all of 

 which ultimately pour their waters into it ; and soluble sub- 

 stances, even such as are theoretically incompatible with each 

 other, being almost in every instance capable of co-existino- in 

 solution, provided the quantities be very minute, I could see no 

 reason why the ocean should not be a general receptacle of all 

 bodies which can be held in solution. And although it will 

 appear from the following account, that I have been unsuccess- 

 ful in some of my attempts to prove the truth of this conjecture, 

 it may fairly be ascribed either to a want of sufficient accuracy 

 in our present methods of chemical analysis, or of the requisite 

 degree of skill in the operator. 



Some time after the communication to which I have just 

 referred, an extraordinary statement was pointed out to me, 

 upon the authority of Rouelle, a French chemist of the last cen- 

 tury, from which it appeared that, mercury was contained in sea 

 salt :f and I saw soon after in the. Annales du Musee, vol. vii. a 

 paper by the celebrated chemist Proust, who, in a great measure, 



• From the Philosophical Transactions for !S22. Part II. 

 + Set Journal dt JMtdecinc, vol. xlviii. 1777, page 32?. 



