3 - PHILOSOPHICAL TRANSACTIONS. [aNNO 1744. 



fire; add a little water by degrees, to dissolve the salt; then boil gently for a 4^ of 

 an hour; add more water, and afterwards 3 lb. of strong quick-lime; let all boil 

 together for a while: when the solution is complete, filtre the lixivium, and eva- 

 porate to a dry powder, as in the first process; put this powder into a tubulated 

 retort; and pour on gradually l^lb. of rectified oil of vitriol; proceed to distil as 

 before: thus you will obtain 8 oz. of a more strong, more acid, and more volatile 

 spirit, than the former, and of a yellowish colour. 



Observations. — 1. The proportions of the several ingredients here set down, 

 Mr. S. found, by repeated trials, to be the best. 5 lb. of alkaline salt are thus 

 absolutely necessary to dissolve 1 lb. of sulphur ; though, when quick-lime is used, 

 as here specified, 4-i-lb. of fixed salt are sufficient; or even 4 lb. if the quick-lime 

 be very good and strong: so much does the lime strengthen the lixivium, or 

 enable it to dissolve the sulphur. 



2. These 2 processes differ somewhat considerably, as to the quantity and 

 quality, both of the spirit and caput mortuum they afford. The spirit made with 

 lime is less in quantity, but specifically heavier, and yet more volatile, than the 

 other: and the caput mortuum with lime is much whiter, purer, and fitter for 

 making the tartarus vitriolatus, than that made without lime. 



3. By mixing 1 lb. of fixed alkali with the sulphur at first, boiling them a little, 

 and filtring the liquor, then adding 2 lb. more of the salt along with 2 lb. of lime, 

 he found that the sulphur sooner dissolved, than if he put the whole quantity in 

 at once; and thus, after the 2d filtration, he put in the rest of the salt and lime, 

 till all the sulphur is dissolved; as finding this the readier way to perfect the 

 solution. 



4. In the distillation, a little of the sulphur will sometimes sublime into the 

 neck of the retort ; and this seems owing either to making the fire too fierce at 

 the beginning, or using the oil of vitriol too weak: but such a sublimation of the 

 sulphur is no further detriment to the operation. 



5. When lime is used in this process, a considerable proportion of fixed alkaline 

 salt may be saved, the spirit will be rendered stronger, and the caput mortuum 

 cleaner and whiter, so as to make an excellent tartar of vitriol, by solution, 

 filtration, and crystallization. But it must be observed, that the produce of this 

 tartar of vitriol, when prepared, is not near so large as when no lime has been 

 used in it; and accordingly he found, that the dry powder, remaining after the 

 solution and evaporation of the sal alkali and sulphur alone, weighed as much as 

 they did originally : whereas, when lime has been used, the remaining powder 

 has weighed half a pound less than the original weight of the sulphur and fixed 

 salt; which seemed a curious phenomenon; and might lead to farther discoveries 

 of the relation between lime and fixed alkaline salt, &c. 



6. The advantages of this method, in respect of M. Homberg's, are, (l.) That 



