so2 Sir Benjamin Thompson’s Experiments 
frefh water, I was defirous of feeing what variation it would 
occafion in the refult of the experiment, if, inftead of remov- 
ing the air from time to time, I fufFered it to remain in the 
globe till the end of the experiment : to this end I made 
Experiment N° 1 4. 
I11 which the globe being filled with frefh water, and the 
filk ufed in the laft experiment (being firft well wafhed), the 
whole was expofed four days to the action of the fun’s rays, 
the weather being remarkably fine, and very hot. Upon re- 
moving the air produced, I found it amounted to 30^ cubic 
inches ; and its quality, proved with nitrous air, was la + ^n 
r= 1,02, or 298, 
I fhould have continued the experiment for fome days longer, 
as the globe did not appear to be exhaufted ; but the quantity 
of air already collected in the globe was fo great that it became 
very difficult to remove it, without running the rilk of lofing 
a part of it, or of letting the air of the atmofphere enter the 
globe, either of which would of courfe have fpoiled the expe- 
riment. For fafety therefore, and that I might not by an acci- 
dent lofe the trouble I had already had with it, I put an end 
to the experiment at the end of the fourth day. 
The water had loft of its tranfparency, and had acquired a 
greenifh caff, as in the laft experiment ; and in both thefe 
experiments I obferved, that a confiderable quantity of wbitifh 
yellowiffi earth was precipitated by the water, which, falling to 
the bottom of the globe, attached itfelf to the glafs in fuch a 
manner that it was with difficulty that it could be removed. 
Thefe were general appearances, and took place in all cafes, in 
a greater or lefs degree, where a confiderable quantity of pure 
air was feparated from water by the influence of light. 
4 Expe- 
