ANALYSIS OF BRITISH AND FOREIGN SALT* £Q5 



neck 10 inches long. Sixteen cubic inches of water (each 

 252| grains at 6'0° Fahrenheit) filled the whole of the globe, 

 and about half an inch of the lower part of the neck ; and 

 from the line where the water stood in the instrument, it 

 was accurately graduated upwards into hundredth parts of 

 a cubical inch. Into this vessel I poured exactly sixteen 

 cubic inches of a perfectly saturated solution of common 

 salt; and then added 400 grains of the salt under examina- 

 tion, washing down the particles that adhered to the neck 

 by a portion of the liquid, which had been previously taken 

 out of the globe for the purpose. As much as possible of 

 the air which adhered to the salt was dislodged by agitation; 

 and the increase of bulk was then observed. 



Care was taken, that the salts were all of equal tempera- 

 ture and dryness, and that no change of temperature hap- 

 pened during the experiment. 



(-400 grains of the less pure kind of rock ofTcJtUn' "pecifif ^fi^***** 



\ salt, broken down into small trag- grav.was* 



J meuts, tilled the space of 75 2112 



} 400 grains of stoved salt 75 2112 



1 400 do. (another sample) 76 2084 



V.400 do. common salt . - • 76 20S4 



C 400 large grained fishery salt 83 190# 



J 400 do. (another sample) 83 1909 



(400 St. Ube's 82 1932 



If the above mode of determination at all approach to 

 correctness, it would appear, that the specific gravity of 

 rock salt is diminished, by being broken into small frag- 

 ments, from 2125 to 2112, probably in consequence of the 

 quantity of air which the fragments envelope, and which 

 cannot be entirely separated by agitation. From the num- 

 bers given in the last column, it is evident, that the smaller 

 grained salts are specifically heavier than those which are 

 composed of larger and more perfect Crystals. A difference 

 of only one or two hundredth parts of a cubic inch is per- 

 haps entitled, in a process of this kind, to little reliance; 

 and I do not therefore regard it as indicating any material 

 difference in the specific gravity of the first four, or last 



* Distilled water at 1000 being taken as the standard. 



three 





