1820.] Mr. Dalton oti Sulphuric Ether. 129 



which agree very well with each other, and with the mean of 

 my two theoretic tables. As for the force of steam below 212°, 

 .no one has found any material variation from those in my first 

 table ; indeed scarcely any one seems to have attended much to 

 those below 100°, Avhich 1 was most anxious to have correct. 

 The force of steam at 32° is an important element ; I have spent 

 much time and labour upon it, both before and since my first 

 table was pubhshed ; it is not less, I think, than 0*2 of aii inch, 

 nor more than 0-3 ; these being- the extremes of my experiments; 

 perhaps 0-25 is very near the truth. 



IVIy table of the force of alcoholic vapour represents it too 

 high for temperatures below 60°, and for those above rather too 

 low. These errors arose partly from the alcohol not being free 

 from water, and partly from a mistake, as I now apprehend, in 

 fixing a standard mark on the alcohol Ijarometer. I'hey are but 

 small, and of little importance, as the observations were not used 

 in establishing general principles. An improved and more 

 extended series of observations on the force of alcohol vapoui^ 

 has recently been published by Dr. Ure, as mentioned above, the 

 results of which fall in as well as can be desired with those from 

 water, in establishing a general law that the vapours of homoge- 

 neous liquids expand in geometrical progression to equal inter- 

 vals, or at least to the same intervals of temperature. 1 may add, 

 my own experiments recently made for the first time, corrobo- 

 rate those of Dr. Ure in the interval of temperature from 175° ta 

 212°.* 



The following skeleton of a table of the force of vapour from 

 water, alcohol, and ether, is formed from what 1 consider as the 

 most correct experiments hitherto made on these subjects, and 

 may have its use, though it will be found not to differ very mate- 

 rially from my former tables, except where they differ from each 

 other. 



experiments on ether also, in corrnboratioo of my early experiments, aod of the- 

 general principles ihence derived ; a stronjjer condemnation of those p.rinciples 

 could not have heen brou^Iit forward than their agreement uith (he results of Dr. 

 Ure on ether vapour. All tlie information we have given a-; to the qualitj , &c. of 

 his ether is contained in the following paragraph. " The ether of the shops, as. 

 prepared by theeminent London apothecaries, boils generally at 112°; but when 

 wajtied with water or redistilled, it boils at 104° or l6j°. It may Uy rectification, 

 however, be made to boil at a still louer temperature." We are presented «itl\ 

 two series of experiments on the fi)rce of ether vapour ; the first b?^ins at S4°n:itt». 

 the force 6-2, and ends at 104°, with the force of 30 inches of mercury; the second 

 begins at 10.i° witli the same force, and ends at 210° with the fr>rce of 166 inches. 

 What the specific gravities of the two kinds of ether used were, and whether the- 

 ethers used were obtained from the very inferior ether of 112° by washing, or by 

 distillation, are important points, concerning which we-jve nrt informed. How- 

 ever, Dr. Ure contrives to blend these two disjointed series, and to compare the 

 results with those of mine made upon ether which boi'jpcl at 98° ; and finding; great 

 di»crep;incrs, he concludes my results on ether and j)rinciplcs deduced fiuni ibenv 

 are pregnant with errors. 



• Philosophical Transactions, 1818. 



Vol. XV. N°II. 1 



