240 PHILOSOPHICAL TRANSACTIONS. [aNNO 1675. 



with spirit of wine, and the solution of saltpetre still more. The same experi- 

 ment was also made with common water, mixed in vacuo with aquavitag purged 

 of air, when the ebullition was also found to be very great. It is somewhat re- 

 markable, that common water mixed with aquavitae, and put within the vacuum, 

 bubbles up very well, though the former be there in greater quantity than the 

 latter; whereas, a mixture of aquafortis and aquavitae did not there bubble up at all. 



In order to know whether these ebullitions produced any new air; a gauge 

 was put into the receiver, which is a glass tube, filled either with water freed of 

 air or with mercury, 4 inches long; and it was observed, that when the liquors 

 were mixed together, the water in the gauge rose very nimbly to the top ; and 

 then exhausting this new air, the gauge, water subsided again by degrees, in 

 like manner as when the common air is drawn out: and thus it was found, that 

 all these kinds of ebullition produce an air which expands itself like common air.* 



It seems remarkable, that the air produced by these ebullitions, is not all of 

 the same nature. For it has been found experimentally, that the air formed by 



* On this occasion it may be noticed, as it is recorded in the journal book of the Royal Society, 

 An. 1668, April 30, that Mr. Boyle gave an account to the said Society of the experiments he had 

 then made about generating new air, or extricating that air which was lurking before in several 

 bodies : at which time he mentioned also some ways of examining whether the substance thus pro- 

 duced be true air or not. And long before that time, viz. An, 1664, the 15th of March, as appears 

 by the same journal, Mr. Boyle mentioned to the Royal Society that corals or oyster shells pounded, 

 and put into distilled vinegar, might prove fit substances to produce air wholesome for breathing. At 

 which time he also proposed, that some fit animal might be put into a receiver of his exhausting 

 engine, and the air pumped out till the creature grew sickish ; and that then some new air might be 

 produced in the receiver by a contrivance of making distilled vinegar work upon tlie substances be- 

 fore-mentioned J to see whedier by this means die animal would recover. 



About the same time Sir Christopher Wren also suggested, to put a. fermenting liquor in a glass 

 ball, and to fit a stop-cock to it, and tie a bladder about the top of the stop-cock, by which means 

 the air, to be generated by the fermenting liquor, would pass into the bladder, and on the turning of 

 the stop-cock be kept there in the form of air, Mr, Hook also mentioned several liquors, which by 

 their working on one another would produce an air 3 as oil of tartar and vitriol j spirit of wine and 

 turpentine. And he made before the Royal Society the foUowing experiment : He took a common 

 glass phial with two pipes, and some pounded oyster shells and aquafortis ; and as soon as the latter 

 was by one of those pipes poured on the former, and the hole stopped with good cement, the 

 ebullition caused by the shells being corroded by the aquafortis, in a very little time blew up the 

 bladder, tied on to the other pipe, so as to swell it very plump with air ; which expansion remained 

 till the Society rose, after they had ordered the vessel to be carefully locked up till their next meet- 

 ing, which being tlie week after, the bladder was then found somewhat shrunk. The like experi- 

 ment was made with bottled ale, supposed to yield a more wholesome air for respiration, &c, — ^Orig.f 



f The elastic fluid extticated in the instances mentioned in this note is not common or atmospheric air, but fixed air 

 or carbonic acid gas ; a species of air unsuited to the purposes of respiration, and even deleterious to animals that are 

 placed in an atmosphere of it and compelled to breathe it, though but for a short space of time. 



