304 



Mr. Griffin on the Constitution of 



Observations on the Table of Muriatic Acid. 



Muriatic acid has only one-third part of the solubility of 

 sulphuric acid. A saturated solution of the latter contains 

 about 24 test atoms, that of the former only about 8 test atoms 

 per decigallon. The condensing power of muriatic acid is 

 only a tenth part of that of sulphuric acid, and though always 

 progressing with dilution, yet when the acid forms the hy- 

 drate containing 6000 atoms of water, where the dilution is 

 about 800 fold, the entire condensation does not amount to 

 10 septems. The atomic measure at the highest is about 1\ 

 times that of water, and at the lowest is not less than twice 

 that of water. 



The limited solubility of certain substances in water has 

 been sometimes ascribed to the action of cohesion, but it is 

 difficult to conceive in what manner cohesion can limit the 

 solubility of muriatic acid gas. The two upper lines in Table 

 IV. exhibit a singular illustration of the effects of cohesion. 

 The compression of 40 atmospheres at 50° F. is required to 

 reduce muriatic acid gas to a liquid of sp. gr. 1'27 3 in which 

 condition the test atom measures 51*2 septems, and the deci- 

 gallon contains 19^ test atoms. The compressive power of 

 water acting on the gas at about the same temperature, and 

 under the ordinary pressure of the atmosphere, reduces the 

 anhydrous acid to sp. gr. 1*6963, in which condition its test 

 atom measures only 38*33 septems, and the decigallon con- 

 tains 26 test atoms. We may judge from this fact that the 

 limited solubility of muriatic acid in water results, not from 

 the cohesion of its particles, but from a quality the very oppo- 

 site to cohesion. 



The fraction which -f- 1 indicates the mean specific gravity 

 of 100° of muriatic acid is (-6963--26-089 = ) -026688. 



Table V. Showing the increase of Specific Gravity occa- 

 sioned in Solutions of H 2 CI 2 by condensation. 



Atoms of 



H«ei2. 



7-00 

 600 

 500 



Increase in 

 spec. grav. 



•002284 

 •006072 

 •007360 



Atoms of 

 H.2CR 



4-00 



31969 



300 



Increase in 

 spec. grav. 



•008048 

 •008680 

 •007736 



Atoms of 

 H2C12. 



200 

 100 

 010 



Increase in 

 spec. grav. 



•006524 

 •004012 

 •000531 



The point of greatest condensation in muriatic acid is at 

 that hydrate which distils without alteration in constitution. 

 Mitscherlich (perhaps after Dalton) quotes this hydrate as 

 sp. gr. 1-094, composition = H 2 C1 2 + 17£H 2 Q. Professor 

 Clark states the specific gravity to be 1-110, and its composi- 

 tion = H 2 Ci 2 + 16f H 2 0. It may possibly be H 2 C1 2 + 16H 2 0. 

 The hydrate, where the greatest density is united with the 



