·03 185 199 7·06 ·04 139 154 5·42 ·05 111 125 4·44 ·06 93 107 3·78 ·07 79 93 3·31 ·08 70 84 2·96 ·09 62 76 2·69 ·10 56 70 2·46 ·11 51 65 2·29 ·12 46 60 2·14 ·13 43 57 2·01 ·14 40 54 1·90 ·15 37 51 1·81 ·20 28 42 1·48 ·25 22 36 1·29 ·30 19 33 1·16 ·40 14 28 1·04 ·50 11 25 ·89 ·60 9 23 ·89 ·70 8 22 ·78 ·80 6 20 ·72 1·00 5·5 19·7 ·70 Mr Wanklyn’s process for the determination of carbonic acid in the atmosphere is as follows:——A solution of carbonate of soda is first made as follows: 4·47 grammes of gently-ignited carbonate of soda are dissolved in one litre of water, giving a solution of such a strength that 1 c. c. contains exactly 1 c. c. of carbonic acid (= 1·97 milligrammes of CO_{2}); a large quantity of baryta water (strength about 0·1 per cent.) is prepared. If now 100 c. c. of clear baryta water be treated with 1 c. c. of carbonate of soda, just described, a certain degree of turbidity is produced. If 2 c. c. of the solution be taken another degree of turbidity is produced, and so on. If, then, a bottle capable of holding 2000 c. c. of air, together with 100 c. c. of baryta water, be filled with the sample of air to be tested, there will be a certain depth of turbidity produced by shaking it up. Having got the air to expend itself on 100 c. c. of baryta water the degree is to be found by comparison with another 100 c. c. of baryta water, in which a like turbidity has been induced by means of the standard solution of carbonate. Every c. c. of soda solution counts for a c. c. of carbonic acid in two litres of air. A consumption of 1 c. c. will correspond to ·05 volumes of carbonic acid per cent. Good air should accordingly not take more than 1 c. c. of soda solution, air which takes already 2 c. c. being already bad.