308 



Mr. Griffin on the Constitution of 



stals remelted, recrystallized, abstracted once more from the 

 mother-liquor, and finally brought into solution in a closed 

 bottle at 62° F., and not heated higher than that point. The 

 specific gravity of the solution thus procured was 1*058286, 

 and its chemical strength 955°, which gives the formula 

 C 4 H 6 3 + 1-178 H 2 0, showing nearly one-fifth part of an 

 atom more water than belongs to the protohydrate. Repeated 

 trials brought me no nearer to the protohydrate, which I 

 imagine is partly owing to the difficulty of separating the 

 mother-liquor entirely from the crystals. Van der Toorn 

 (Report of the Fourth Meeting of the British Association, 

 Edin. 1834) states the specific gravity of the protohydrate at 

 59° F. to be 1*057, which makes its strength to be 979°. 

 This is possibly correct, and 1 have inserted it in the Table, 

 in company with the specific gravity of the anhydrous acid, 

 calculated from Van der Toorn's number. Of course the an- 

 hydrous acid is hypothetical. 



The weaker solutions of acetic acid were prepared by dilu- 

 tion of the strong acid in stoppered graduated glass cylinders. 

 The quantity of acid contained in each diluted solution was 

 determined by neutralization with weak ammonia of known 

 strength, applied by means of a pouret; the mixing being 

 effected in a stoppered glass bottle, and solution of litmus 

 being employed to test the point of neutralization. All the 

 adjustments, measurements and weighings were effected at 

 62° F. 



The fraction which + 1 indicates the mean specific gravity 

 of 100° of acetic acid is (-067645 -*- 11*6194 =) -005822. 



Table IX. Showing the increase of Specific Gravity occa- 

 sioned in Solutions of C 4 H 6 '0 3 by condensation. 





In acetic acid, the greatest chemical strength, the greatest 

 density and the greatest condensation characterize three dif- 

 ferent hydrates. None of the mineral acids possess this sin- 

 gular divergence of properties. The greatest chemical strength 

 is the property of the protohydrate of 979° (Van der Toorn), 

 or according to my experiments at 62° F., of the solution of 

 955°. The greatest density is at about 800°, where the hy- 

 drate has nearly 3 atoms of water. The greatest condensation 



