The quantity of real acid it contained is then deduced by the following calculation:——One equivalent of gaseous carbonic anhydride, or anhydrous carbonic acid (= 44) bears the same proportion to one equivalent of the acid in question, as the amount of the carbonic anhydride expelled does to the amount of the acid sought. Thus, suppose a dilute sulphuric acid expels 3 gr. of carbonic anhydride, the arrangement is—— 44 : 49 :: 3 : 3·349 Consequently the sample operated on contained 3·5 (nearly) grains of true sulphuric acid. Instead of the above calculation, we may multiply the weights of the respective acids required to expel 1 gr. of carbonic acid (as exhibited in the following table) by the number of gr. of dry carbonic acid evolved during the above operation. The product represents the per-centage strength, when 100 gr. of the acid have been examined. When only 50, 25, 20, or 10 gr. have been tested, this product must, of course, be doubled, quadrupled, &c., as the case may be. TABLE II. Multipliers. Acetic acid (anhydrous) 1·159 ” ” (hydrated or glacial) 1·364 Citric acid (crystallised) 1·523 Hydrochloric acid (dry or gaseous) ·829 ” ” (sp. gr. 1·16) 2·478 Nitric acid (anhydrous) 1·227 ” ” (sp. gr. 1·5) 1·523 ” ” (sp. gr. 1·42) 2·045 Oxalic acid (crystallised) 1·432 Sulphuric acid (anhydrous) ·909 ” ” (sp. gr. 1·8485) 1·114 Tartaric acid (anhydrous) 1·500 ” ” (crystallised) 1·705 Even this easy calculation may be avoided, in technical analysis, by simply taking for the assay such a weight of the respective acids as is capable of disengaging exactly 10 gr. of dry carbonic acid from the bicarbonate. In this case, the loss of weight in grains, from the operation, multiplied by 10, at once indicates the exact per-centage strength sought. The proper weight of any acid to be taken to give per-centage results is found by simply dividing ten times the equiv. of that acid by 44. For, taking sulphuric acid as an example, as—— 44: 49 :: 10 : 11·1318 or 11·13 nearly. On this principle are obtained the weights to be taken, as given in—— TABLE III.