1835.] on Spirits. 261 



does not advance us one step to the attainment of our 

 object, as it simply substitutes one maker's instrument in 

 place of another, leaving the vast interests depending upon 

 its indication to the accuracy of the maker, or perhaps, his 

 workman. We have no other method of settling this dis- 

 puted point, but that of ascertaining the specific gravity 

 of spirit indicated as proof at 60° by this instrument. 



In different trials, we have found this to vary from *91936 

 to '91978, or rather, spirits within this range were all 

 indicated as exactly proof by the hydrometer, evidence 

 that it is not sufficiently delicate to show very small varia- 

 tions, but decisive enough in proving, that the specific 

 gravity deduced by the latter of the above views *91957 at 

 60°, is that of legal proof spirits, and therefore, containing 

 by weight, Alcohol . . . 49-2 



Water. . . . 50-8 



100-0 



When it is considered, that by the above act, Sikes' 

 hydrometer is made a national standard, it becomes in- 

 teresting to inquire, how far from the accuracy in its 

 relative indication, or its intrinsic merit, it is entitled to 

 such a distinction. 



This hydrometer like every other, is simply a sp. gr. 

 instrument, indicating the difference between the weight 

 of an equal bulk of water, and of the liquid under trial. 

 In place, however, of being so graduated as simply to give 

 this, which is all that the instrument is capable of doing, 

 the whole range of specific gravity which it takes in has been 

 divided into one hundred parts. This, at the very first, has 

 the obvious disadvantage of rendering its indication quite 

 unintelligible, but through reference to a voluminous set 

 of tables which accompany it, and which give the per 

 centage as it is called, over or under proof, at every 0*2 

 of each of these hundred divisions. 



There is some difficulty in exactly defining the terms, 

 over and under proof, which are consequently very often 

 misunderstood. If we mix 50 measures of proof spirit 

 with 50 measures of water, from the concentration which 

 takes place, this mixture will not be 50 per cent, under 

 proof, but only 49. Again, if to 50 measures of proof 



