go Sir Benjamin Thompson’s Experiments 
airs may amount to i meafure, and may not be greater than 2 
meafures, there are two marks upon the phial, made with the 
point of a diamond, the one (hewing I meafure of my eudio- 
meter, the other (hewing 2 meafures. 
The tube of my eudiometer is half an inch in diameter in- 
ternally, and 1 meafure occupies 3! inches in length upon it, 
and the meafure itfelf is made of a piece of the fame tube. 
Both the one and the other are ground with fine emery on the 
infide, in order to take off the polifh of the glafs, and by that 
means facilitate the running down of the water, which might 
otherwife hang in drops upon the infide of the tube upon the 
introduction of air. 
The nitrous air was always frefih made, and of the fame 
materials, viz. fine copper wire di(folved in fmoking fpirits of 
nitre, diluted with 5 times its volume of water ; and all pofii- 
ble attention was paid to every other circumflance that could 
contribute to the accuracy of the experiments. 
I have thought it neceflary to mention thefe particulars oil 
account of the great difference in the apparent goodnefs of any 
kind of air proved by the ted; of nitrous air, which arifes from 
the difference of the circumftances under which the experi- 
ments are made. 
But to return to my experiments upon the air produced upon 
expofing filk in water to the aClion of the fun’s rays. 
1 
Experiment N° 2. 
Finding that the quantity and the quality of the air produced 
depended, in a great meafure, upon the intenfity of the light 
by which the water and the filk were illuminated, I was defi- 
rous of feeing whether by depriving them intirely of all light, 
they would not at the fame time be deprived of the power of 
furnifhing 
