€58 Description of an Umv6rsal Hydrometer. 



weight of the wood in air will be 42 grains ; and if on fijf* 

 ing it to the screw beneath, the instrument requires 325 

 grains to sink it to the mark in water, (being 28 grains 

 more than would be necessaiy to sink the instrument itself,) 

 we have only to find the difference between the weights put 

 into the top cup, which in this case is 70 grains ; and di- 

 viding 42 by 70, we have -C or 'COO for the specific gravity 

 of the wood. 



For the man of science, the instrument with its set of 

 weights is all that is necessary, and it is packed info a 

 very small compass * ; but to accommodate it to those who 

 are concerned with spirituous liquors, and to brewers, the 

 inventor attaches a scale, showing the relation between spe- 

 cific-gravities and the commercial or technical denomina- 

 tions of /)(??• centage with the former, and pounds per barrel 

 with the latter. 



It is needless to enumerate the various departments in 

 which an attention to the specific gravities of bodies is now 

 become of the first consequence, and wherein this instru- 

 ment might be applied with advantage; and although many 

 may be satisfied if they have any arbitrary standard to regulate 

 iheir process by, yet it most be acknowledged that the uni- 

 versal standard of specific gravity is by far the best ; for, by 

 its currency all over Europe, it enables a person to know 

 what relation their practice may bear to that of others in the, 

 same pursuit ; and it would, by the universal adoption of 

 it, prevent the many differences which exist among mer- 

 cantile men, especially those who deal in, or pay duty on, 

 spirituous liquors. 



Indeed ihe wide field which opens, on considering the 

 importance of paying attention to the specific gravity of 

 bodies, convinces us that we are yet in infancy 011 the 

 subject, 



* The price of it is five guineas. 



XLVIII. De- 



