Description nf an Universal Hydrometer. 255 



polarity, and consequent derangement by magnetism ; the 

 expansion of either arm by the heat cf the hand, or its con- 

 traction by a current of air, renders those instruments ex- 

 tremely liable to give anomalous results. 



But supposing the balance not liable to error, it is too 

 complicated in its use for any other than the man of science, 

 in his closet, where time and close attention may be af- 

 forded ; and since the application of science to the arts has 

 become so general, chemists-, manufacturers of acids, brew- 

 ers, dyers, distillers, and all others whose manufacture con- 

 sists of any chemical process, require a more simple and 

 c.xpedilioui mode of ascertaining the specific gravity, and 

 consequently the value of their articles, than by the hy- 

 drostatic balance. Indeed, in many concerns its use would 

 be impracticable, it being necessary to intrust the business 

 of examining the qualities of the substances in question to 

 persons who have neither time or knowledge sufficient to 

 enable them to apply an instrument of such a kind. 



The HYDROMETER, on a Variety of constructions, has been 

 long made use of by distillers and all dealers in spirituous- 

 liquors; and of late years brewers have generally adopted 

 it, for its simplicity and facility in use compared with the 

 hydrostatic balance or weighing bottle. But as the hydro- 

 meter for spirituous-liquors, and the saccharometer for malt- 

 liquors, (which the author of this paper is in the habit of 

 manufacturing,) are adapted solely to tlieir respective pur- 

 poses, he has long thought it a very desirable object lo con- 

 siruct an instrument which would combine simplicity with 

 an universality of application to all substances, fluid and 

 solid, of which it might be requisite to ascertain the specific 

 gravity. And it is presumed that this object is accomplished 

 in the instrument about to be described. 



Among the principal subjects of consideration in the 

 construction of hydrometers, are, the form of the instru- 

 ment which shall be best adapted to facilitate its motion In 

 a fluid, and that it be of a convenient size, both for the 

 sake of portability, and that it may require as small a sample 

 of a fluid as possible to make an experm)ent with. 



With these views, the spheroidical form is that which 



has 



