103 



able eiTors of his manual operations, and authorize him to eliminate 

 from the essential elements of a compound those products of an ana- 

 lysis whose quantity cannot be reduced to any admissible proportion, 

 and may therefore be considered as extraneous. 



The author, at the close of his paper, controverts the opinion of 

 those who think that crystallization requires a previous state of solu- 

 tion in the matter crystallized ; and contends, that as long as any 

 quantity of fluid is present in a solution, no crystallization can pos- 

 sibly take place. 



Experiments on the Quantity of Gases absorbed by Water, at different 

 Temperatures, and under different Pressures. By Mr. William 

 Henry. Communicated by the Right Hon. Sir Joseph Banks, K.B. 

 P.R.S. Read December 23, 1802. [Phil. Trans. 1803, p. 29.] 



After a short recapitulation of what has of late been done by 

 Mr. Cavendish, Dr. Priestley, Dr. Nooth, and others, respecting the 

 impregnation of water with different gases, our author observes, that 

 the circumstance of the different degrees of temperature and pressure 

 had not been as yet sufficiently attended to. Dr. Priestley, indeed, 

 had long since remarked, that, in an exhausted receiver, Pyrmont 

 water will actually boil at a common temperature, by the copious 

 discharge of its air ; and that hence it is very probable, that by means 

 of a condensing engine, water might be much more highly impreg- 

 nated with the virtues of the Pyrmont spring : but this conjecture 

 remained as yet to be proved by experiments ; and this is the task 

 our author has undertaken in the present paper. 



This paper consists of two sections ; the first treating of the quan- 

 tities of gases absorbed by water under the usual pressure of the 

 atmosphere ; and the second, of the influence of pressure in promoting 

 the absorption of gases. The apparatus contrived for these experi- 

 ments may be described as a siphon, of which one side, or leg, is a 

 glass vessel of comparatively a considerable diameter, and the other 

 a long glass tube of about a quarter of an inch bore ; the junction 

 of these two parts at the bottom being a short pipe of India rubber, 

 well secured by proper integuments of leather, thus forming a joint, 

 which admits of the vessel being briskly agitated. This vessel has 

 a stop -cock both at top and bottom, in order to insert and emit fluids 

 and gases ; and both the vessel and tube are accurately graduated. 

 It may now be. understood, that a known quantity of water and of a 

 certain gas being put in the vessel, and the tube being filled to a 

 certain extent with mercury, the absorption of the gas will be accu- 

 rately measured by the column of mercury in the tube. Those who 

 are particularly interested in this inquiry will find in the paper va- 

 rious precautions and additional contrivances, all tending to insure 

 the success and accuracy of the investigation. 



The first experiments were made on the absorption of carbonic 

 acid gas by water : and here a singular disagreement was observed 

 in the first trials made under exactly the same circumstances. It 



