[ 1 S* ] 



head, he never found that it contained quite fo much 

 as half its bulk of this air. If a fufficient quantity 

 of quickfilver cannot be procured, oil may be ufed 

 with fufficient advantage, for this purpofe, as it im» 

 bibes the fixed air very flowly. Fixed air may be 

 kept in vefTels ftanding in water for a long time, if 

 they be feparated by a partition of oil, about half an 

 inch thick. Pyrmont water made in thefe circum- 

 ftances, is little or nothing inferior to that which has 

 flood in quicklilver. 



The readiejl method of preparing this water for 

 ufe is to agitate it ftrongly with its whole furface ex- 

 pofed to the fixed air. By this means alfo, more than 

 an equal bulk of air may be communicated to a 

 large quantity of water in the fpace of a few mi- 

 nutes. Eafy directions for doing this I have published 

 in a fmall pamphlet, defigned originally for the ufe 

 of feamen in long voyages, on the preemption that 

 ' it might be of ufe for preventing or curing the lea 

 fcurvy, equally with wort, which was recommended 

 by Dr. Macbride for this purpofe, on no other ac- 

 count than its property of generating fixed air, by 

 its fermentation in the ftomach. 



Water thus impregnated with fixed air readily 

 diffolves iron, as Mr. Lane has difcovered ; fo that if 

 2 quantity of iron filings be put to it, it prefently 

 becomes a ftrong chalybeate, and of the mildeft and 

 mofl agreeable kind. 



I have recommended the ufe of chalk and oil of 

 vitriol as the cheapeft, and, upon the whole, the beft 

 materials for this purpofe ; and whereas fome perfons 

 had fufpe&ed that a quantity of the oil of vitriol 

 was rendered volatile by this procefs, I examined it 



by 



