166 Dr. Dalton on the Constitution of the Atmosphere, 



An ingenious pupil of mine, Mr. William Barnett Watson of 

 Bolton, has succeeded in uniting lime and sulphur by heat; 

 instead of taking pounded lime, which has a harsh gritty feel, 

 he takes hydrate of lime, and expels the water by a red heat 

 continued till 32 parts of hydrate are reduced to 24? ; this is a 

 fine soft powder; when 24? parts of this pure and finely di 

 vided lime freed from water are well mixed with 24- parts of 

 sulphur and heated red in a covered crucible, a partial com- 

 bination takes place, and an increase of weight to the lime ; 

 this operation is to be repeated till the additional weight be- 

 comes 14 grains, after which no further addition can be ef- 

 fected. Mr. Watson found it require several repetitions. I 

 have since found it may be effected by two or three only. This 

 sulphuret is not used in eudiometry. 



Quadrisulphuret of Lime, in the humid *way. 



When sulphur and hydrate of lime in almost any propor- 

 tions are boiled together in water, quadrisulphuret of lime is 

 formed and dissolved in the water ; the solution is of a deep 

 yellow colour, and has a very bitter taste. 1 have not seen 

 in any author the proportion that ought to be used, nor the 

 quantity and specific gravity of the liquid solutions. These 

 are subjects which have engaged my attention. If lime is in 

 excess, the liquid consists of lime-water holding in solution 

 quadrisulphuret of lime. If sulphur is in excess, the hquid 

 consists of water holding in solution quadrisulphuret of lime. 

 I have long known that the ceconomical proportions to be used 

 are 32 parts of dry hydrate of lime by weight with 56 of sul- 

 phur, that is, one atom of lime with four atoms of sulphur. 

 If more lime than that above be used, it will be found preva- 

 lent in the residue; if more sulphur, then the redundant sul- 

 phur will be found in the residue. A few ounces of the mixed 

 ingredients may be gently boiled in an iron pan for an hour 

 or more, stirring the liquor occasionally, and covering the 

 pan with a lid to prevent the too free admission of atmospheric 

 air. Or, in order to prevent the action of oxygen on the 

 liquid, a flask may be substituted for the pan ; the materials 

 may be put into the flask nearly filled with water, and the 

 flask loosely corked may be immersed in a pan of boiling water 

 so as to be almost covered by the water. The liquor to be pre- 

 served should be kept in green glass bottles, nearly full, and 

 having ground stoppers. After the boiled liquor has cooled 

 and the sediment subsided, the clear liquor may be decanted, 

 if it be strong or deep coloured the sediment may be washed 

 with a little water, and another quantity of the liquor obtained 



