VOL. LXXXII.] PHILOSOPHICAL TRANSACTIONS. 263 



fluid, which, either alone or mixed with air, affects the manometer by pressure 

 and the hygrometer by moisture, without any difference arising from the pre- 

 sence or absence of air ; at least without any hitherto perceived." 



XXII. Supplementary Report on the Best Method of Proportioning the Excise 

 on Spirituous Liquors. By Charles Blagden, M. D., S. R. S. p. 425. 



The report to which this paper is intended as a supplement, was drawn up, and 

 published, when the experiments on the specific gravities of the spirituous liquors 

 had been continued only to equal quantities of alcohul and water by weight. It 

 was foreseen that a further set of experiments, on more dilute liquors, would be 

 wanted : but as these must necessarily take up a considerable time, the persons 

 concerned thought it best to submit those already made to the public; that if any 

 errors or inaccuracies should be discovered, they might be avoided, and if any 

 person should suggest a better method, it might be adopted, in the subsequent 

 proceedings. Want of ice, and some other hinderances, prevented the experi- 

 ments on what may be called watery mixtures from being entered on earlier than 

 the beginning of last winter. Fresh spirit was distilled for the purpose by Mr. 

 Schmeisser, who brought some of it to the specific gravity of .817 ; but it had a 

 smell somewhat different from that employed in the former experiments, and 

 more approaching to the odour of ether. On inquiry it was found that, whereas 

 Dr. Dollfuss had drawn the former spirit off vegetable alkali, Mr. Schmeisser 

 used Glauber's salt calcined by exposure to the air. In order to try whether this 

 circumstance made any difference in the quality of the new spirit, Mr. Gilpin 

 mixed some of it with an equal weight of water, and afterwards brought the mix- 

 ture to all the different temperatures from 30° to 100°, operating in the same 

 manner as he had done with Dr. Dollfuss's spirit ; when the specific gravities 

 were found to come out the same. Mr. Schmeisser's alcohol therefore was used 

 without hesitation. As no censure had yet been passed on the former experi- 

 ments, the same general method was pursued for the new series ; with a small 

 variation however, the reason of which is now to be explained. 



In the report on the first experiments Dr. B. introduced the following remark. 

 " It must be observed, that Mr. Gilpin used the same mixture throughout all 

 the different temperatures, heating it up from 30° to 100°; hence some small 

 error in its strength may have been occasioned, in the higher degrees, by more 

 spirit evaporating than water ; but this, it is believed, must have been trifling, 

 and greater inconvenience would probably have resulted from interposing a fresh 

 mixture- The consciousness that such a source of error existed, made them de- 

 sirous of ascertaining to what quantity it amounted, by some previous experi- 

 ments, before the new set should be begun. These showed that it was somewhat 

 greater than had been supposed, though not such as ever to cause a difference of 



