II Y DRODYNAMICS. 



cieux's hy- 

 drometer. 



PLATE 

 CCCXIV. 

 Fig. 2. 



Junes'! hy- 

 drometer. 



Fig. 3. 



4. Deparctetts'j Hydrometer, 



This instrument, which was intended by its author 

 for measuring the specific /rravities of different kinds of 

 water, is represented in Plate CCCXIV. Fig. 2. where 

 AB is a glass phial about seven or eight inches long, 

 and two inches in diameter. It is loaded with shot at 

 the bottom to prevent it from overturning, and its lower 

 part is rounded to prevent the air from lodging below. 

 A brass wire AC, about 30 inches long, and T 'T f * n 

 inch in diameter, is fixed in the cork of the phial, which 

 is well varnished to prevent the penetration of the wa- 

 ter. The length of the wire ought to be such, that, 

 when the phial is loaded and immersed in spring wa- 

 ter at a medium temperature, the whole phial, and about 

 an inch of the wire, should be below the scale, while, 

 when it is plunged in very light river water, the wire 

 should be immersed about 20 inches. To the sum- 

 mit of the wire is fixed a cup C, which contains the 

 small weights with which it may be found necessary 

 to load the instrument in order to make it sink to a 

 fixed point in different kinds of water. A tube of white 

 iron DEFG, about 3 feet long, and 3 inches in diame- 

 ter, is used to hold the water whose specific gravity is 

 to be determined, and there is attached to it a scale 

 EH, divided into inches and parts of an inch, for the 

 purpose of measuring the different depths to which the 

 instrument sinks. This instrument is so sensible, that, 

 if a small quantity of spirits of wine, or a pinch of su- 

 gar or salt, are added to the water in the tin tube, the 

 phial will ascend or descend a very sensible quantity. 

 M. Deparcieux made use of a hydrometer which weighed 

 23 ounces, 2 gros, and 26 grains (French). A weight 

 of 38 grains made it descend through a height of 19 

 inches, 6 lines, which was equal to 6 T ' 7 lines for every 

 grain, or the -^^th part of the volume of water dis- 

 placed. The results given in our general Table of 

 specific gravities, p. 455, for different waters in France, 

 were obtained by means of this instrument. See Prony's 

 Architecture Hydraulique, torn. i. 614 627. 



5. Jones's Hydrometer. 



This hydrometer, which was invented by Mr Wil- 

 liam Jones of Holborn, is constructed so as to apply the 

 correction which is necessary from a change of tempe- 

 rature. This correction had hitherto been applied only 

 in a rough manner ; but upon considering that 32 gal- 

 lons of spirits in winter will expand to nearly 33 gal- 

 lons in summer, Mr Jones fixed a thermometer to his 

 instrument, and by adjusting the divisions experimen- 

 tally, he has obtained it pretty correctly. Mr Jones has 

 also taken into account the diminution of bulk which 

 takes place in mixing alcohol and water, which is so 

 great as to produce a loss of four gallons in the 100. 

 Thus, if to 100 gallons of spirit of wine, which are 66 

 gallons in the 100 over proof, 66 gallons of water are 

 added to reduce it to proof spirit ; the compound of 

 water and alcohol will consist only of 162 gallons in- 

 stead of 166, four gallons having been lost by the mu- 

 tual penetration of the two fluids. 



Mr Jones' hydrometer is represented in PlateCCCXIV. 

 Fig. 3. It consists of a stem AC of the form of a pa- 

 rallelopipcd, on the five sides of which the different 

 strength of spirits are marked. One of these sides is 

 shewn in Fig. 3. and the other three separately. This 

 stem is fixed to the oval ball CD, which is made of hard 

 brass, and has its conjugate diameter about one and 

 a half inches. A thermometer DE is attached to the 



stem DB below the ball, and the whole length AB of HycUome. 

 the instrument is about 9^ inches. Three weights tcrs - 

 W, W, W" are suited to the three sides of the stem * 

 shewn separately. Let us now suppose that the in- Jones's hjr. 

 strument is plunged in a spirituous liquor ; then, if it drometer. 

 floats, so that the surface of the liquor is somewhere be- PLATE 

 tween A and C, the division on the side of the stem CCCXIV. 

 marked (viz. the side of the stem attached to the in-, Fi o- 3 - 

 strument) will indicate the strength of the liquor if it 

 is between 74 gallons in the 100, and 47 in the 100 

 above proof. But if the surface of the fluid stands be- 

 low the extremity C of the scale, it must be loaded with 

 any of the weights W, W, W", till the surface of the 

 liquor rises above C ; then, if the weight W, or No. 1. 

 is required to produce this effect, the side of the stem 

 marked No. 1 . will shew the strength of the spirituous 

 liquor from 46 gallons in the 100 to 13 in the 100 above 

 proof. If the weight No. 2. is required to raise the sur- 

 face of the spirits above C, the divisions on the side 

 marked No. 2. will shew the strength from 13 gallons 

 in the 100 above proof to 29 gallons in the 100 under 

 proof; and if the weight No. 3. is required, the divi- 

 sion on the side marked No. 3. will shew the strength 

 of the spirits from 29 under proof down to water, which 

 is marked W at the bottom of the scale No. 3. The 

 thermometer DE has four scales engraven upon it, 

 marked No. 1, 2, 3, corresponding with the similarly 

 numbered scales on the stem. Two of these scales only 

 are seen in the figure. The zero or of each scale is 

 at the middle of each column, and corresponds with a 

 temperature of 60 of Fahrenheit ; then whatever num- 

 ber of divisions the mercury in the thermometer stands 

 above the zero, so many gallons in the 100 must the 

 liquor be reckoned weaker than the hydrometer indi- 

 cates ; and whatever number of divisions the mercury 

 in the thermometer stands below the zero, so many 

 gallons in the 100 must the spirits be reckoned stronger 

 than the hydrometer indicates. 



The diminution of bulk occasioned by the mutual 

 penetration of the two fluids, is marked by the small 

 figures on the different scales of the stem. Thus the 

 figures 2^ at 48, 3^ at 61, and 4 at 66, indicate, that if 

 the spirit be 48 gallons in the 100 over proof, the bulk 

 of the compound will be 2^ gallons less than the sums 

 of the two ingredients, that is, instead of being 148 it 

 will be 145^. This instrument is adjusted, like other 

 hydrometers, to the temperature of 60 of Fahrenheit> 

 and requires only three different weights to determine 

 the strength of spirituous liquors from alcohol to water. 



6. Dicas's Hydrometer. 



The hydrometer constructed by Mr Dicas of Liver- Dicas's by- 

 pool, possesses all the advantages of Jones' hydrometer, drometer. 

 but exhibits, with more accuracy, the correction which 

 it is necessary to apply for a change of temperature. It 

 is constructed of metal, with a stem and ball of the or- 

 dinary form. It has 36 different weights, which are 

 valued from to 370, including the divisions on the 

 stem ; but the chief improvement which distinguishes 

 this hydrometer is its ivory sliding scale, which adjusts 

 it to different temperatures, and indicates the diminu- 

 tion of bulk arising from the mutual penetration of the 

 combined fluids. 



7. Quin's Universal Hydrometer. 



The object of this hydrometer is to ascertain with Quin's uni- 

 the greatest expedition the strength of any spirit from vereal hy- 

 alcohol to water, the diminution of bulk, and the spe- 

 cific gravity of each different strength, and also the 





