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1825.} Di\ Prout on a new Portable Hydrometer. 335 



constructed for the purpose, of which the following is a sum- 

 mary description. 



Fig. 1, represents the instru- 

 ment of its natural size. There .^^ 

 is nothing peculiar in its con- 

 struction but the scale; the \-^W \S^ 

 numbers on which are always 

 to be added to 1000,the assumed 



sp.gr. of water. Thus suppos- ii j Uj^ 



ing the number cut by the sur- 

 face of the fluid be 30, this 

 indicates that its spec. gras'. 

 is 1030, water being 1000, 

 &c. 



Fig. 2, represents the other 

 side of the scale. W (opposite 

 on the other side) is the 

 point at which the instrument 

 stands in pure water. H S 

 or healthy standard, is the 

 mean point about which healthy 

 urine usually ranges. The 

 portion of the scale marked 

 diabetes is that to which the 

 instrument rises in diabetic 

 aftections, &c. 



Thus by the aid of this little 

 instrument can every thing 

 connected with the specific 

 gravity of the urine be easily 

 determined in a few seconds to 

 a degree sufficiently accurate 

 for all practical purposes. The 

 scale is graduated for the mean 

 temperature of 60°; but the 

 instrument may be used at all temperatures between 40° and 

 80 without any error of practical importance. When used, care 

 should be taken to prevent the adhesion of air bubbles, and the 

 scale should be depressed helo,o the point at which it naturally 

 stands in the fluid, m order that the instrument may rise to that 

 point. Ihe degree then cut (after it has stood a few seconds) 

 by the surface of the fluid as seen from below is the specific gra- 

 vity. When the operation is completed, the instrument is to be 

 dipped into common water, and wiped dry to prevent the corro- 

 sion ol the metallic part. 



1 am, Gentlemen^ your obedient humble servant, 



W. Prout. 



