d^ 



Scientific IntcUiyence, 



[Nov. 



Chaussier '7980, but assuming the mean, the proposed standard 

 would contain nearly one-half by weight of absolute alcohol. 



The committee considers the hydrometer the best instrument in 

 the hands of the excise officer for ascertaining the specific gravity. 

 Bate's hydrometer, by means of a scale of 50 parts and 18 weights 

 or poises, has a range of 900 divisions, ajid expresses specific gravities 

 at the temperature 62", while Sike's instrument has a scale of 500 

 divisions only, and yet these are smaller than on Mr. Bate's instru- 

 ment. " Hence, the facility of reading the more extensive scale on 

 Bate's instrument, is greater than with the more limited scale of 

 Sike." Mr. Bate has constructed the weights (which in this instru- 

 ment are immersed in the fluid) of different specific gravities, so that 

 each successive weight should have an increase of bulk over the pre- 

 ceding weight, equal to that part of the stem occupied by the scale, 

 and an increase of weight sufficient to take the whole of the scale 

 and no more down into the liquid. This arrangement requires great 

 accuracy of workmanship, and enhances the price of the instrument. 

 As it can only however, ascertain specific gravities at the tempera- 

 ture of 62o, it would be inexpedient to use the term specific gravities 

 for the numbers it would show ; the term indication, being that 

 already in use, would be much better, and involve no risk of ferror. 

 The committee recommends attention to the accuracy of the thermo- 

 meters employed.* It advises the construction of three tables for 

 practical purposes. The first, which shall indicate the same strength 

 of spirit at every temperature ; not however, expressing the quality 

 of the spirit by any number over or under proof, but marking at once 

 the number of gallons of standard spirit, contained in, or equivalent 

 to 100 gallons of the spirit under examination. Thus, instead of saying 

 23 over proof, it is proposed to insert 123, and in place of 35-4 under 

 proof, to insert 64 6, as is illustrated in the following table: — 



strength, at any temperature, relative to a standard bulk of 100 



* That thennometers are liable to become inc. rrect in the course of time, has 

 been much insisted on, since the publication of the observations made at Geneva 

 on this subject. Dr. Thomson has, liowever, shown that tliis does not hold good 

 with regard to the accurately constructed thermometers of Crichton of Glasgow, 

 even after a lapse of forty years. See on Heat and Eleclricily, [J. 40. — Edit. 



