'igS PHILOSOPHICAL TRANSACTIONS.: j_ANNO 1766. 



a middle-sized hand to pass through it, from the abdomen, for a small space, be- 

 tween its anterior edge and the convolutions of the lower extremity of the sto- 

 mach, and the semicircular turn it made to the pylorus, with the beginning of 

 the duodenum from thence, and the other extremity of the duodenum, before 

 the jejunum commenced, and that part of the colon which returned into the 

 pelvis; all of which were lodged in the very aperture: so that the space left un- 

 occupied by these parts could not be much less than 8 inches in circumference: 

 notwithstanding which, very little of a watery fluid was found in the sac: indeed 

 it would not have had a very easy admittance, from the many adhesions formed 

 between the sac and its contained parts, a little below the opening from the 

 abdomen. 



XIX. Three Papers, containing Experiments on Factitious Air. By the Hon. 

 Henry Cavendish, F.R.S. p. 141. 



By factitious air, says Mr. C, I mean in general any kind of air which is con- 

 tained in other bodies in an unelastic state, and is produced from thence by art. 

 By fixed air, I mean that particular species of factitious air, which is separated 

 from alkaline substances by solution in acids, or by calcination; and to which 

 Dr. Black has given that name in his treatise on quicklime. As fixed air makes a 

 considerable part of the subject of the following papers; and as the name might 

 incline one to think that it signified any sort of air which is contained in other 

 bodies in an unelastic form; I thought it best to give this explanation before I 

 went any farther. 



Before proceeding to the experiments themselves, it will be proper to mention 

 the principal methods used in making them. In order to fill a bottle with the air 

 discharged from metals or alkaline substances by solution in acids, or from animal 

 or vegetable substances by fei-mentation, I make use of the contrivance repre- 

 sented in pi. 5, fig. 13, where a represents the bottle, in which the materials for 

 producing air are placed; having a bent glass tube c ground into it, in the man- 

 ner of a stopper; e represents a vessel of water; d the bottle to receive the air, 

 which is first filled with water, and then inverted into the vessel of water, over 

 the end of the bent tube; pf represents the string by which the bottle is sus- 

 pended. When I would measure the quantity of air produced by any of these 

 substances, I commonly do it by receiving the air in a bottle, which has divi- 

 sions marked on its sides with a diamond, showing the weight of water required 

 to fill the bottle up to those divisions: but sometimes I do it by making a mark 

 on the side of the bottle in which I have received the air, answering to the sur- 

 face of the water in it; and then, setting it upright, find how much water it 

 requires to fill it up to that mark. 



In order to transfer the air out of one bottle into another, the simplest way. 



