the Strengths and Values of Spirituous Liquors, 3 1 1 



^■"as by no means conducive to their accuracy. The surface 

 of a slender stem is proportionally greater when compared 

 with its solid content tlian that of a small one : the capillary 

 attraction, therefore, and the weight of the liquor which 

 adheres to it, both operate more powerfully. If we take 

 any of those instruments whose stem is a mere wire, we 

 shall find them, from the^e causes, so sluggisli in their mo- 

 tion that they will generally stand at any point of the stem 

 at which they are placed, within a quarter of an inch of a 

 certain part of it, whereas those with a thicker stem regain 

 the same poiiat instantaneously. The tliickcr the stem, 

 therefore, the better, so as it be only within such limits as 

 to render the difference in the jx)ints at which the instru- 

 ment will stand, in two liquors which difler in a very minute 

 degree with respect to their specific gravities, sufficiently per- 

 ceptible. 



Let us calculate for a moment how many weights we 

 must have to a spirit hvdrometer. The stem may very con- 

 veniently be 4 inches long, and in this length we could 

 easily graduate 40 or 50 divisions, so that a difference of 

 one-fourth of each shall be very visible. But we want to 

 express a difference of nearly 200 in specific gravity (or from 

 800 to 1000) by this instrument within about one-fourth of 

 an unit. VVe shall therefore do it extremely well by the 

 virtual lengthening of the stem to four or five times its real 

 length by means of three or foijr weights. It is true, the 

 divisions, unless they be arbitrary ones with a scale of re- 

 ference, are not equal ; if they be units of specific gravity, 

 they must be graduated frorii several harnjonic scales ; but 

 this will not affect the truth of our general deduction ; and 

 three or four weights, therefore, will be fully suiiicieiit for 

 the nicest spirit hydrometer, whatever scale of graduation 

 we may use on its stem. 



This kind of instrument would be far preferable, even if 

 superior accuracy were alone the object, if simplicity were 

 entirely out of the question, and 40 weights as easy and as 

 little liable to error in their application as 4 : but when we 

 reflect that simplicity and facility of use are, perhaps, even 

 of more consequence than accuracy in the result, the dif- 

 ference in the advantages of these modes of constructiorj 

 becomes enoriijous. 



It has been a favourite opinion with some gentlemen, 

 that glass hydrometers would be preferable to metallic ones, 

 because they would not be liable to have their bulk altered 

 by any contusion without being broken to pieces ; whcteas 

 the latter mi^ht be so delved by rough usage a« to give faU 

 \J 4 lacioua 



