Another method for estimating the strength of the sample of acid is by weighing the amount of carbonic acid expelled during saturation. (Method of Fresenius and Will.) This depends on the weight of gaseous carbonic acid which a given weight of the acid-sample under examination is capable of expelling from pure bicarbonate of soda (or of potash), which is estimated by the loss of weight in the acidimeter, or apparatus, after the gas, rendered perfectly dry by passing through sulphuric acid, has escaped into the air. TABLE I.——_Weights of the respective acids equivalent to the given weight of the principal bases, hydrogen being taken as unity._ {51 Acetic acid (anhydrous). {60 ” ” (crystallised or glacial). {99 Arsenious acid (dry). {35 Boracic acid (anhydrous). 17 gr. of pure ammonia.[8] } {62 ” ” (crystallised). 31 ” anhydrous soda.[9] } {22 Carbonic acid (dry). 40 ” hydrate of soda.[9] } {67 Citric acid (crystallised). 53 ” dry carbonate of soda.[10] } {85 Gallic acid (dried at 212°). 143 ” crystallised carbonate of } {94 ” ” (crystallised). soda.[11] } {127-1/2 Hydriodic acid (dry or gaseous). 84 ” crystallised bicarbonate } {27 Hydrocyanic acid (anhydrous). of soda. } {36-1/2 Hydrochloric acid (dry or gaseous). 47 ” anhydrous potassa.[9] } {109 ” ” (liquid, sp. gr. 1·162). 56 ” hydrate of potassa.[9] } are {166-1/2 Iodic acid. 69 ” dry carbonate of potassa.[10]} exactly {54 Nitric acid (anhydrous). 100 ” crystallised bicarbonate } neutralised {63 ” ” (liquid, _monohydrated_, sp. gr. of potassa. } by { 1·517 to 1·521). 50 ” {pure chalk. } {67-1/2 ” ” (liquid, _sesquihydrated_, sp. gr. {pure marble. } { 1·5033 to 1·504). 28 ” pure caustic lime. } {72 ” ” (liquid, _binhydrated_, sp. gr. 37 ” hydrate of lime (fresh). } { 1·486). 44 ” dry carbonic acid (when } {90 ” ” (liquid, sp. gr 1·42). the bicarbonate of } {36 Oxalic acid (anhydrous). potassa or soda is } {63 ” ” (crystallised). used for testing in } {72 Phosphoric acid (anhydrous).