TM 



COLD. 



which it hid held in Solution. The variety in the form 

 " """" of the cryl obtained by former experiments, w there- 

 . v . fore most likely occasioned by the presence of these fo- 



l.Hl CI pC* . . 



substance*, phenomenon not uncommon in che- 



on 

 the frr*. mistry. 



The result of these experiments led me now to per- 

 ceive, that the assumption that alcohol, prepared by Rich- 

 ter's process, is perfectly pure, or at most contains only 

 a very minute portion of water, is entirely gratuitous. 

 The diluted alcohol of commerce, from which the more 

 concentrated is obtained, is well known to contain diffe- 

 rent volatile impurities ; and since Kichter's process makes 

 DO provision for the separation of these, we ought rather 

 to expect still to meet with some portion of them in alco- 

 hol prepared in this manner. 



I next proceeded to examine the properties of the dif- 

 ferent substances into which I had separated Richter's 

 alcohol, but the time I had now left for this purpose was 

 too short for making much progress in this inquiry ; a few 

 only of their habitudes with water, and with one another, 

 were all that I had time to examine ; even these I could 

 examine only imperfectly. 



The lowermost stratum, or nearly colourless fluii 1 , 

 which I have called alcohol, had no flavour, and produ- 

 ced on the organ of smell only a sharp pungent sensation. 

 it has the remarkable property of smoking when expo- 

 sed to the air, and, when diluted with water, it differs 

 considerably in taste from common diluted spirit of wine. 



I have made no experiments to ascertain the specific 

 gravity of this alcohol. It may at first sight be conclu- 

 ded, that, by being deprived of its impurities, which are 

 evidently specifically lighter than it, this alcohol would 

 have its specific gravity increased : such a conclusion, 

 however, would be obviously rash ; for, since these impu- 

 rities were, without doubt, previously in combination with 

 the alcohol, and when mixed with it again enter into that 

 state, and since, by this kind of combination, the mean 

 specific gravity is generally altered, most frequently in- 

 creased supposing that this combination follows the 

 more general law, the increase may be either greater or 

 less than the diminution occasioned by the lighter impu- 

 rities ; and therefore, for any thing we at present know, 

 the specific gravity of this alcohol may be either greater 

 or less than that of the compound from which it is ob- 

 tained. 



The pale yellow substance, or second stratum, has a 

 pnngent taste, leaving an impression of sweetness. It 

 has a very strong but agreeable smell. When mixed 

 with the alcohol, and diluted with water, it has very 

 much the flavour of the better kinds of highland whisky. 

 It readily dissolves in water, and communicates to thai 

 fluid its peculiar flavour. 



The pale yellowish green substance which composes 

 the uppermost stratum, has a strong and very offensive 

 smell, and a very sharp nauseous taste. It dissolves in 

 alcohol, to which it communicates its peculiar flavour ; 

 its disagreeable smell is considerably heightened by this 

 combination. It dissolves in water, though less readily 

 than the substance last treated of. The compound, when 

 much diluted and heated, has very much the flavour of 

 the luv nine of our lowland distillers, at the time when 

 it issues from the still. 



The two last mentioned substances, or those of which 

 the two upper strata are composed, when mixed together 

 and greatly diluted with water, have very nearly the fla- 

 vour of alcohol. They have rather more volatility than 

 water ; for when half of a solution of them has been 

 distilled over, the distilled part has a much stronger smell 

 than that which rcmair.t in the retort. The kind of 



smell, however, of both portion! it the same, which Cold. 

 shows that these impurities cannot be separated by dis- w -.- 

 filiation. 



It may be proper to mention, that from the circum- 

 stance of my sense of smell having been for some time 

 extremely obtuse, I have been under the necessity of 

 trusting to others for the facts regarding the flavour of 

 these new substances and mixtures. From the uniform- 

 ity of the reports, however, which I have received from 

 different persons, I have no doubt that these facts arc 

 correct. 



Besides that from which I filled the thermometer in 

 the first experiment, I have operated on alcohol of tlie 

 specific gravities 802, 797, and 78k the specific gravi. 

 ty of the last was taken when its temperature v 

 and it is probably the most concentrated that ha 

 been obtained. But with alcohol of all these differ' 

 strengths, the general results were similar. In alcohol 

 obtained from different sources, the proportions of the 

 impurities were different, both with regard to the pure 

 alcohol, and to one another, but I have met with nom- 

 inal did not contain both. 



From these experiments I think it is ascertained, 



1st, That the strongest alcohol which we are able I* 

 obtain, may be fro/.en by the method alluded to. 



2d, That this alcohol contains at least two foreign 

 substances, which are highly volatile, and, so far as is 

 known, can only be separated by freezing. 



3d, That it is to these substances that alcohol owes its 

 peculiar flavour, and that, according as the one or other 

 predominates, the flavour of the alcohol is agreeable or 

 otherwise. 



Last autumn (of 1812) I resumed this subject, and my 

 attention was chiefly directed to the habitudes of these 

 impurities with the chemical re-agents. This I found at- 

 tended with considerable difficulties, none of the least of 

 which was to procure a sufficient quantity of these impu- 

 rities in a separate state. The scries of experiments 1 

 proposed to myself on this subject have not yet been com- 

 pleted, but I may remark, that the result of some of those 

 I have made promises to afford practical hints of consi- 

 derable importance to those brewers, whose products are 

 intended to afford spirituous liquors. 



From this notice it will be observed, that I have 

 scarcely yet entered on the wide field of inquiry, for the 

 cultivation of which, the method alluded to appears to 

 offer so powerful an instrument. Alcohol only has been 

 subjected to experiment ; it was the only liquid which 

 had resisted all attempts to reduce it to the solid state by 

 the abstraction of caloric. If these experiments be cor- 

 rect, we may now pronounce it a general law to which 

 there is no exception, that all liquids with which we are 

 acquainted, may be reduced to the solid state by a suit- 

 able abstraction of caloric. Whether all gases may be 

 susceptible of reduction to the -solid state, by the abstrac- 

 tion of caloric, remains to be ascertained ; although, as I 

 have mentioned, analogy renders .it in the highest degree 

 probable." 



Before finishing the consideration of artificial cold, we R,,];,,^ 

 must offer a few remarks on a fact, the explanation of of cold. 

 which seems to have given a great deal of difficulty to 

 chemists, we mean the apparent radiation of cold. The 

 discussion of this subject is important, in a scientific 

 point of view, from its connection with the question con- 

 cerning the existence of a frigorific principle, as an anta- 

 gonist to caloric. We do not pretend that we shall sat 

 this question at rest; but we arc satisfied we shall be able 

 to prove, that the existence of cold, as a separate and ic- 



