114 Dr. Henry's Analysis of several Varieties 
reel heat, and afterwards dissolved in a large quantity of boil- 
ing distilled water, yields, when precipitated by a barytic salt, 
in the proportion of 175.9 grains of sulphate of barytes from 
100 of the calcareous sulphate.* The same quantity of ignited 
sulphate of lime ( — 128 grains dried at 160° Fahrenheit,) 
precipitated by super-oxalate of potash, gives 102.5 of oxalate 
of lime ; or, precipitated by sub-carbonate of potash at a boil- 
ing heat, 74.3 grains of carbonate of lime.-f- One hundred 
grains of crystallized sulphate of magnesia (=56 desiccated) 
afford when precipitated by muriate of barytes, 111 or 112 of 
the barytic sulphate. 
(E.) By a comparison of the above proportions with those 
obtained in the analysis of any specimen of common salt, we 
may learn whether it contain other sulphates beside those with 
earthy bases. For example, if the precipitate (D.) consist of car- 
bonate of lime only, and bear to the sulphate of barytes (C. b.) 
the proportion of 74 to 1 75, or very nearly so, we may infer, 
that no other sulphate is present, but that of lime. The same 
conclusion will follow, if, after having decomposed one half 
of the watery solution (C. ) by muriate of barytes, and another 
half by oxalate of potash, we find that the sulphate of barytes 
bears to the oxalate of lime, the proportion of 175.9 to 102.5. 
* This result corresponds, within a fraction of a grain, with one obtained in a 
somewhat different way by Dr. Marcet, and very nearly with an experiment of my 
friend Mr. James Thomson, who found the barytic sulphate, precipitated from too 
grains of sulphate of lime by nitrate of barytes, to weigh 173 grains. 
f On reversing this experiment, I found that 100 grains of carbonate of lime, sa- 
turated with sulphuric acid, and calcined in a low red heat, afford 135 of sulphate of 
lime. A similar experiment of Mr. Thomson gave 134.6 grains. Dr. Marcet, 
also, informs me that from 93.55 grains of pure marble, he obtained 125.95 grains 
sulphate of lime, proportions which exactly co-incide with those of Mr. Thomson. 
