1823.] On the Compositimt of certain Muriates^ 339 



Article III. 



On the Composition andEquivaleni Numbers of certain crystallized 

 Muriates, By R. Phillips, FRS. L. and E. &c. 



While correct views of the nature of chlorine and most of 

 its compounds have been derived from the researches of Sir H. 

 Davy, it appears to me that the attention of chemists has not 

 been sufficiently directed to the consideration of the nature of 

 some compounds which may be considered either as muriates 

 or as chlorides containing water. In the first volume of the 

 Annals, N. S. I gave a statement of the different views which 

 may be entertained of those salts, which must be regarded 

 either as chlorides or muriates. I now return to the subject, 

 from having lately had occasion to employ the salt usually called 

 muriate of barytes in such proportions as contained a certain 

 quantity of the earth. 



In order to ascertain the equivalent number of this salt, I 

 Consulted Dr. Thomson's table of the weights of atoms, given in 

 the last volume of his System of Chemistry ; in this we find the 

 composition of chloride of barium, but not of muriate of barytes ; 

 and under the head of muriate of barytes (vol. ii. p. 254)* the 

 reader is referred to chloride of barium for a description of it. 

 "The easiest method of preparing it," says Dr. Thomson, 

 " would be to dissolve carbonate of barytes in muriatic acid, 

 and crystaUizing the solution." "The primitive form of this 

 chloride," he continues, " is, according to Haiiy, a four-sided 

 prism, whose bases are squares, tt crystalhzes most commonly 

 in tables." (System, vol. i. p. 357.) From this quotation it is, 

 I think, evident, that Dr. Thomson considers the crystaUized 

 muriate (for so at present I shall continue to call it) as a mere 

 chloride, and he does not mention that it contains any combined 

 water : he certainly observes, " that when heated, it decrepi- 

 tates and dries," but this seems merely to refer to accidental 

 moisture. 



On Dr. Wollaston^s scale, dry muriate of barytes is mentioned, 

 and this is of course the chloride of barium, for the number by 

 which it is^ represented agrees as nearly with that assigned by 

 Dr. Thomson to the chloride as 131 to 132-5 In the memoir in 

 which the scale is described by its author, crystallized muriate 

 of barytes is represented as consisting of muriate of barytes 

 131 +2 water = 22*6; making the number for crystallized 

 muriate of barytes 153*6 ; it is singular that Dr. Wollaston has 

 not placed this upon the scale, for as the salt usually occurs in 

 the crystallized state, it is that in which it is most used, and in 

 which the knowledge of its equivalent is most desirable. Mr. 

 Brande (Manual, vol. ii. p. 82), appears to agree with Dr, Thorn- 



z2 



