IVl i'HILOSOPHlCAL TRANSACTIONS. [anNO 176*. 



grains, we shall find, that in this process IS-^Yr cubic inches of air were ex- 

 tracted from 371^ cubic inches of the Pouhon water. From this experiment 

 it appears, that a very large quantity of air is contained in the Pouhon water: and 

 a way is pointed out whereby the proportion of the bulk of air to that of a cer- 

 tain quantity of water, from which it had been extracted, may be exactly deter- 

 mined. Although this proportion must vary considerably in many waters, 

 according to the weight and heat of the atmosphere, or the dryness or moisture 

 of the season, at the time that they are taken from the fountain ; and will also 

 vary with the different degrees of expansion of the atmosphere, at the times 

 that the different quantities of air are measured; Dr. B. does not, therefore, 

 give the above proportions for such as always hold; neither does he assert that 

 they most commonly take place. He rather suspects the contrary; and, from 

 other trials, is apt to believe, that a larger proportion of air is usually con- 

 tained in the Pouhon water, than that which he obtained in the above experi- 

 ment. For, when a boiling heat was used, the necks of the bladders were apt 

 to shrivel, and became liable to crack on the least motion; so that it was diffi- 

 cult to confine the air in them. Had he had an opportunity at Spa of prose- 

 cuting this experiment further, he should have attempted to have extracted all 

 the air by a milder heat of about 1 ] degrees, in phials inverted in the water 

 bath; so as that, while the air arose into the phials, an equal portion in bulk of 

 the water might have been received into bladders fitted to them ; or should have 

 made use of other methods, which he shall have occasion hereafter to describe. 

 Exper. 4. He took a glass receiver, of a cylindric form, near 5-i- inches high, 

 and 3|- inches in diameter, which contained 25 oz. 1 50 grs. of water, Troy 

 weight; or in measure 45-|fi cubic inches, according to the above calculation of 

 265 grains of water to the cubic inch. This receiver being immersed in a cis- 

 tern of water, was there turned, with its mouth downwards, and then raised, 

 through a hole in a board fitted to the top of the cistern. The receiver was 

 there firmly secured with wedges, in such manner as to continue full of water, 

 the lower part of it remaining immersed in the water of the cistern. He then 

 took a Frontiniac phial, which contained IQ oz. 5 drs. of water: this was filled 

 with fresh pure air, by emptying it of the water in a cool open place, and then 

 stopping it with a cork. The phial, thus filled with air, was placed in an erect 

 position under the receiver; and the cork being taken out, the air ascended into 

 the receiver, as it was forced out of the phial by the water rushing into it. Into 

 this air a mouse was conveyed, by placing it on a round piece of cork, and 

 plunging it quickly through the water into the receiver, in which it floated on 

 the cork. In this air it lived for an hour in great ease, breathing with freedom, 

 and diverting itself, while wet, with drying its face and head with its paws^ like 

 a cat. After having thus lived an hour in this close prison, it was taken out of 



