67 



them otherwise ; but as to those in common use, or which are found natu- 

 rally existing, I think it would be better retaining the old names. And with 

 regard to salts whose properties alter according to the manner of preparing 

 them, such as corrosive sublimate, calomel, &c. &c., I should in particular 

 think it very wrong to attempt to give them names expressive of their com- 

 position. 



As I think this attempt a very mischievous one, it has provoked me to go 

 out of my usual way & give you a long sermon. I do not imagine, indeed, 

 that their nomenclature will ever come into use ; but I am much afraid it will 

 do mischief, by setting people's minds afloat, & increasing the present rage 

 of name-making. 



EXPERIMENTS ON AIR. 



[These experiments occupy about 100 sheets, of 4 pages each, of which some 

 are blank, in whole or in part : they are numbered and indexed, as well as 

 written, by Cavendish's hand : their arrangement is generally in the order of 

 time, but on making a second experiment to the same effect as one made be- 

 fore, he has sometimes entered it out of that order, on a blank page, after the 

 first : thus at page 128 an experiment of Nov. 1782 is inserted among those 

 made in 1781, of which it was a repetition. The following lithographic ex- 

 tracts contain all his experiments relating directly to the composition of water, 

 & involve all the reasonings of his paper in the Transactions on this subject : 

 the remainder relate chiefly to the analysis of air, and of the gases proceed- 

 ing from charcoal, and from its combustion with nitre. Among those which 

 he did not think it worth while to relate, is one which shows the unsettled 

 state of opinion respecting the general properties of gases,] 



Note-book, p. 80. — " It was tried whether the visinertieB ofphlogisticated 

 was the same in proportion to its weight as that of common air, by finding 

 the time in which a given quantity passed through a given hole, when urged 

 by a given pressure, by means of the following apparatus : — 



" A is a tin vessel, eight and a 

 half inches in diameter and ten 

 deep, with a small hole in the 

 diaphragm, a. This vessel is 

 suspended over a vessel of water 

 by the rod B, turning on a cen- 

 tre near the middle point, and 

 partly balanced by a weight at 

 the other end, and suffered to 

 descend as the air runs through the hole. The time in which it descended 

 a given space (about seven inches and a half), was found by observing the 

 time in which the knob b moved from one mark to another. The force with 

 which the vessel was pressed down*was about ten and a half ounces, the rest 

 of the weight of the tin vessel being taken off by the counterpoise. Tlie way 

 by which it was filled with air was, by holding it under water till all the air 



E 



