HYDROSTATICS. 



finding the specific gravities of bodies, 

 both liquid and solid. See HYDROSTA- 

 TICS. 



HYDROSTATICS relate to the resting 

 equilibrium of non-elastic fluids; and to 

 the pressure of solids immersed therein. 

 A fluid is a body whose parts are infinite- 

 ly minute, capable of dislocation in con- 

 sequence of the smallest force, invariably 

 (when suffered to rest) resuming a per- 

 fect level surface, and presenting an equal 

 resistance throughout every part of the 

 body immersed. 



Philosophers consider fluids to be divi- 

 ded into two classes, viz. the elastic, such 



as air, vapour, and gas ; all which may be 

 compressed more or less: and the inelas- 

 tic, viz. water, mercury, spirits &c. which 

 cannot be compressed ; though by being 

 heated they distend considerably. U may- 

 be proper to observe in this place, that 

 Mr. Canton, in the years 1762 and 1764, 

 Dublished the results of experiments he 

 had made, whereby it was endeavoured 

 to be proved, that all fluids were compres- 

 sible, though in so trifling a degree as not 

 to affect their bulks when under exami- 

 nation. With the barometer at 29, and 

 the thermometer at 50, he declares the 

 following compressions were effected. 



With Spirit of Wine 

 Oil of olives - 

 Rain water - 

 Sea water - 

 Mercury - - 



Spec. Grav. 



- 846 - 



- 918 - 

 . 1,000 . 

 -1,028 . 

 13,595 - 



Comi 



We leave the reader to judge whether 

 it be probable, by any apparatus of hu- 

 man formation, and under human gui- 

 dance, to ascertain that the three mil- 

 lionth parts, said to have been compress- 

 ed, were really so. Indeed, even the 

 sixty-sixth millionth parts, suffered to be 

 compressed in the spirits of wine, must 

 appear extremely doubtful ; "though we 

 cannot but conclude that, as air exists in 

 every atom of nature, more or less, with 

 a sufficient force, every fluid were subject 

 to compression into a smaller space than 

 is occupied by it when perfectly at liber- 

 ty. Speaking generally, the definitions 

 above given may be considered as appli- 

 cable to all cases with which we are ac- 

 quainted; and may, perhaps, be com- 

 pletely true. 



We shall commence the detail, incident 

 to this subject, with an account of the 

 method of obtaining the specific gravities 

 of bodies: that is, by showing the com- 

 parative weights of various solids and 

 fluids, as ascertained by the most care- 

 ful and skilful chemists. The reader 

 must, however, consider the weights as 

 taken at a medium. See GRAVITY, speci- 

 /c, where is given a table of specific gra- 

 vities. 



The reader will observe, that the whole 

 of the above are compared with rain-wa- 

 ter, which appear at 1.000 parts ; but it 

 is very remarkable, that the density of 

 that fluid varies greatly according to its 

 temperature ; and that it by no means af- 

 fords a regular scalo of weight, or of bulk, 



Compression. 

 - - 66 parts in a million 



- - - - 48 ditto 



- - - - 46 ditto 



- - - - 40 ditto 



- - - - 3 ditto 



ken from the observations of Dr. Blagden 

 and Mr. Gilpin. 



proportion to the degrees of heat. T 

 U be seen from the following table, 



This 

 ta- 



We must suppose the water of the 

 Dead Sea to be highly impregnated; 

 since it appears to weigh nearly a fourth 

 more than common sea water. 



The anomalies lay between 32 and 45, 

 and are accounted for by the contraction 

 which takes place in water about to 

 freeze, and its sudden expansion after- 

 wards; by this we understand the cause 

 of bottles, pitchers, &c. being burst, when 

 the water they contain freezes. The dif- 

 ference in bulk between water and li- 

 quors, in the winter and in the summer 

 season, averages about three per cent : 

 hence many great dealers have thought it 

 worth their while to buy only in the for- 

 mer season, when the liquors have been 

 most concentrated. 



