1862.] 189 



place of small diameter, and that undecomposed bisulphide of carbon 

 be present. 



Crystals so prepared appear to be perfectly permanent ; they do 

 not undergo alteration from several weeks' exposure to atmospheric 

 changes. I have not yet obtained them free from adhering lime, as 

 all acids which will dissolve the lime decompose the crystals. They 

 are soluble in water, but cannot be recrystallized from their solution. 

 All the solutions I have yet tried decomposed without crystallizing. 

 Other processes have equally failed to furnish a salt which can be ob- 

 tained dry and pure ; and I am therefore unable at present to furnish 

 reliable concurrent analyses which will establish its formula. 



I have not ventured an explanation of the reaction, because I am 

 not yet acquainted with the compounds produced and their relative 

 proportion. To ascertain whether an explanation based upon a reaction 

 between the elements of water and bisulphide of carbon was tenable, 

 I caused caustic lime to be heated to whiteness in a platinum crucible 

 for two hours, and cooled out of contact with air. When cold, this 

 anhydrous lime was saturated with dry bisulphide of carbon ; and in 

 a short time the lime became of a greenish-yellow colour, showing the 

 progress of a reaction between the dry lime and the bisulphide of 

 carbon. 



Some of the reactions of this salt are remarkable ; and more than 

 one will exhibit the liability to error from the use of any but the most 

 perfectly crystalline, dry, and clean specimens. Baryta-water added 

 in excess throws down from an aqueous solution of the pure salt an 

 amorphous, red, insoluble precipitate quite as brilliant in colour as 

 vermilion. If this be washed directly after precipitation, the colour 

 is retained for a considerable period ; but if left in the mother-liquor, 

 it soon darkens. The washed salt dries a brickdust red. 



If, instead of the perfectly pure lime-salt, a solution of the salmon- 

 coloured compound, which is formed when the salt is prepared in 

 large vessels and with powdery lime, be taken, a brownish-yellow 

 crystalline double salt of baryta and lime is formed, which is very 

 soluble in water. 



Nitrate of baryta gives lemon-yellow crystals in a red-brown mother- 

 liquor with solution of the salmon-coloured mass, but an amorphous 

 dirty grey precipitate in a yellowish mother-liquor with solution of 

 the pure salt. 



