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XXX. A New Table of the Quantities of Acid in Sul- 

 plmnc Add of different Densities, constructed for the 

 Use of Manufacturers ; being the Result of Experiments 

 made with the strongest Sulphuric Acid of Commerce. 

 The specific GraiKfies taken at the Temperature of C0°. 

 By Samuel Farkes, F.L.S. 



To Mr. Tilloch. 



Sir, JlIaving been applied to by several persons in dif- 

 ferent parts of the kingdom, for instructions respecting a 

 mode of ascertaining the quantity of acid in diluted sul- 

 phuric acid. I invariably referred them to Dr. Kirwan's 

 Table, which was published in the year 1703 in the fourth 

 volume of the Transactions of the Royal Irish Academy. 

 This however always proved unsatisfactory, inasmuch as 

 few manufacturers understood how to accommodate that 

 table to the common oil of vitriol, or make it applicable to 

 any practical purpose. This has arisen from the circum- 

 stance of Dr. Kirwan having taken sulphuric acid, as it 

 -exists in sulphate of potass, instead of the strongest oil of 

 vitriol, for his standard of real acid. Having, in my own 

 business, fouucl ihe iiiconvenience of this, I several years 

 ago lormed a Table for my private use, from the sulphuric 

 acid of commerce, bv diluting that acid with several suc- 

 cessive portions cf water; a table which I have ever since 

 employed with j;reat advantage. But as this table was 

 formed at a temperature above the mean temperature of th* 

 atmosi)here, and its range was too confined to be of use in 

 every instance, f resolved to undertake the formation of a 

 new one that would be more generally useful, and that 

 should descend by regular gradations down to the lowest 

 poiiu of dilution th.it any consumed of sulphuric acid 

 would be likely to require*. Having now, at no small ex- 

 pense of time and labour, completed this 'I'able, I shall be 

 obliged if you will hnve the goodness to insert it in the 

 next Philosophical Magazine, as I conceive that it will be 

 accepial)lc and useful to many individuals in various 

 branches of trade and manufacture. 



In making this tabic, I ".night ,iave taken p«rz/?crf sulphuric 

 acid, i. e. such as had undero.one a second distillation ; but 

 as this is an article which isnever employed but for philo- 

 sophical purposes, 1 thought it better to make use of the 



* 'I'ljo fir<t line of tlie Tal'le shiwvs the '■pecific gravity i<i a mixture of 

 one pnrt water and 10'.) parts of sironj: Btilphnric acid. The latter, the 

 tperific (^'ravity of one pHit of sitlplmric acid mixed with iOO parts ot water. 



Vol. 40. No, 173. Sep<. 1812. L common 



