According to Lewes, the maximum amount of ammonia found in the acetylene coming from a dripping generator is 0.95 gramme per litre, while in carbide-to-water gas it is 0.16 gramme: 417 and 70.2 grains per cubic foot respectively. Rossel and Landriset have found 4 milligrammes (1.756 grains [Footnote: Milligrammes per litre; grains per cubic foot. It is convenient to remember that since 1 cubic foot of water weighs 62.321 x 16 - 997.14 avoirdupois ounces, grammes per litre are approximately equal to oz. per cubic foot; and grammes per cubic metre to oz. per 1000 cubic feet.]) to be the maximum in water-to-carbide gas, and none to occur in carbide-to-water acetylene. Rossel and Landriset return the minimum proportion of sulphur, calculated as H_2S, found in the gaseous state in acetylene when the carbide has not been completely flooded with water at 1.18 milligrammes per litre, or 0.52 grain per cubic foot; and the corresponding maxima at 1.9 milligrammes, or 0.84 grain. In carbide-to- water gas, the similar maxima are 0.23 milligramme or 0.1 grain. As already stated, the highest proportion of phosphine yet found in acetylene is 2.3 per cent. (Lewes), which is equal to 32.2 milligrammes of PH_3 per litre or 14.13 grains per cubic foot (Polis); but this sample dated from 1897. Eitner and Keppeler record the minimum proportion of phosphorus, calculated as PH_3, found in crude acetylene, as 0.45 milligramme per litre, and the maximum as 0.89 milligramme per litre; in English terms these figures are 0.2 and 0.4 grain per cubic foot. On an average, however, British and Continental carbide of the present day may be said to give a gas containing 0.61 milligramme of phosphorus calculated as PH_3 per litre and 0.75 milligramme of sulphur calculated as H_2S. In other units these figures are equal to 0.27 grain of PH_3 and 0.33 grain of H_2S per 1 cubic foot, or to 0.041 per cent. by volume of PH_3 and 0.052 per cent. of H_2S. Yields of phosphorus and sulphur much higher than these will be found in the journals and books, but such analytical data were usually obtained in the years 1896-99, before the manufacture of calcium carbide had reached its present degree of systematic control. A commercial specimen of carbide was seen by one of the authors as late as 1900 which gave an acetylene containing 1.12 milligramme of elementary sulphur per litre, i.e., 0.096 per cent, by volume, or 0.102 per cent, by volume of H_2S; but the phosphorus showed the low figure of 0.36 milligramme per litre (0.031 per cent, of P or 0.034 per cent, of PH_3 by volume).