FREEZING OF ALCOHOL. 163 



tained. Some of these I soldered together, using as a hot bolt, 

 a rod of frozen mercury, and sometimes a straw cooled down to 

 a very low temperature. 



It now appeared to me to be an object of some importance 

 to ascertain the form of the crystals which this substance 

 assumes. This I found attended with some difficulties, which 

 I did not anticipate, and attempts to overcome them have led to 

 the discovery of some facts which I did not at all expect. 



The common masses exhibited crystals of different forms ; Xlie alcohol 

 two kinds appeared to predominate, and each was tolerably J?*™?* 1 ] ,nt « 

 distinct hi its kind; but it was not very ea^.y to perceive by strata, 

 what increments or decrements the one could be supposed to 

 pass into the other; a rather casual circumstance, however, 

 explained the source of this variety. Attempting to freeze 

 alcohol by a modification of the general process,- which I con- 

 jectured would yield more regular crystals than the common 

 method, I observed, that before crystallizing, the alcohol 

 separated into three very distinct strata; the uppermost was of 

 a pale, yellowish green, while 'he second was of a very pale 

 yellow colour ; both these strata were very thin ; the last 

 mentioned was rather the thickest ; the lowermost stratum 

 was nearly transparent and colourless, and very greatly exceeded 

 the other two in quantity. After allowing a part of the lower The lower 



stratum, which I conceived to be the pure alcohol, to freeze, I stratum > or 



r ' greater part, 



attempted to pour out the remainder ; but, was prevented by the gave rectan^u- 



upper strata, which proved to be solidified. The lowermost of !ar P r,8niatic 

 these two strata bore some marks of crystallization j the upper 

 had none, and proved so firm, as to resist a straw with which 

 I attempted to perforate it, to open a passage for the subla- 

 tent liquid. On removing part of these superior strata, and 

 decanting the remaining fluid, the crystals of the lower stratum 

 appeared very distinctly to be rectangular prisms of equal planes, 

 a few of them on one side of the glass surmounted by quadran- 

 gular pyramids, but most of them by dihedral summits. This 

 experiment I repeated several times, and the results coincided. 



In order to ascertain whether these phenomena arose from The a'cohol, 

 a decomposition of the a'cohol, or from the separation of fo- had "u-'erei 

 reign substances previously held by it in solution, the pro- no change, 

 ducts of several of these experiments were mingled together 

 in a stoppered matrass ; the whole was then raised to the tern- 

 Vol. XXXIV.— No. J5S. N peratun* 



