VOL, LXXXII.] PHILOSOPHICAL TRANSACTIONS. 267 



When all the experiments had been completed, and the tables here given were 

 just brought into order, an ingenious member of the r. s., scarcely less celebrated 

 for his theoretical knowledge than his skill as an artist, published a pamphlet 

 containing censures on our first experiments, and proposing other methods, as 

 much superior to those we had adopted.* In drawing up the report, in order to 

 avoid prolixity, the reasons for choosing some of the methods were not given, 

 where they did not seem likely to be a subject of controversy ; but this pamphlet 

 makes it necessary to assign the motives of our preference, that the public may 

 judge how far we are justified. 



First, as to the proportions of the mixtures: which were made by taking an 

 equal quantity of spirit in every instance, and adding to it successively larger 

 quantities of distilled water, as far as to an equal weight ; with the intention of 

 going through the watery mixtures on the same plan. This was done for the 

 following reasons: 1. Because it was thought more likely to avoid blunders, if 

 the quantity of only one of the ingredients was changeable, that the operator 

 might not have his attention distracted with computing and weighing out 1 dif- 

 ferent quantities for each mixture. 2. Because by this progression the experi- 

 ments come closer together about the medium degrees of strength, where it was 

 supposed most accuracy would be wanted for practice. 3. As it was thought, 

 from the first, that the best method of adjusting the duty would be by the abso- 

 lute quantity of alcohol in any mixture, rather than the proportion per cent., or 

 the strength above or under proof, we judged it most expedient not to make the 

 mixtures on either of the last 2 mentioned principles, lest an undue bias should 

 be given to the judgment, merely from the mode of conducting the experiments. 

 No real difficulty can arise in forming tables of any kind out of these numbers, 

 which answer to an harmonic progression of strength. If the operation be tedious, 

 to obtain the specific gravity of any single proportion, per cent, or otherwise, of 

 alcohol and water, the trouble of reducing the whole to a table would not be 

 great, and when once executed, it is done for ever. 



Secondly, though the chief reasons for making the mixtures by weight, rather 

 than by measure, have been already assigned in the report, it is now proper to 

 add something further on that subject. Nothing but arithmetic is required for 

 obtaining the proportions by measure with the utmost exactness; and, as in the 

 former case, though the operation be a little laborious singly, the computation 

 of the entire table will be sufficiently easy. Such a table was recommended in 

 the report, and can be constructed by any person tolerably conversant with figures. 

 In the pamphlet mentioned above, a method is recommended for proportioning 

 the mixtures by measure, while the actual quantity of spirit is determined by 

 weight, at one operation. The idea is ingenious, but in the execution it seems 



* An Account of Experiments to determine the Specific Gravity of Fluids; by J. Ramsden.— Orig. 



M M 2 



