Let _x_ = vol. of superolefiant, _S_ its sp. gr. _y_ = vol. of carb. hydrogen, ∫ its sp. gr. _z_ = vol. of carbonic oxide, _c_ its sp. gr. & _u_ = vol. of hydrogen, _s_ its sp. gr. _C_ = specific gravity of the mixture, _g_ = oxygen, _a_ = carbonic acid, and _w_ = whole volume of mixture as before. Then we have _x_ + _y_ + _z_ + _u_ = _w_ 4½_x_ + 2_y_ + ½_z_ + ½_u_ = _g_ 3_x_ + _y_ + _z_ = _a_ and _Sx_ + ∫_y_ + _cz_ + _su_ = _Cw_. Whence _u_ = (3_S_ + 5_c_ - 8∫)_a_ - (4_c_ - 4∫)_g_ - (3_S_ + 6_C_ - 6∫ - 3_c_)_w_ -------------------------------------------------------------------- 8∫ + _c_ - 3_S_ - 6_s_. The value of the hydrogen being obtained, it may be subtracted from _w_, and the remainder will be best divided into three portions, by the preceding formula. HEAT PRODUCED BY THE COMBUSTION OF GASES. Subsequent experience to that detailed at page 77, Vol. 1. has furnished the following more correct results of the heat produced by the combustion of pure gases. Hydrogen, combustion of it raises an equal volume of water 5° Carbonic Oxide 4½ Carburetted Hydrogen, or Pond Gas 18 Olefiant Gas 27 Coal Gas (varies with the gas from 10° to) 16 Oil Gas (varies also with the gas from 12° to) 20 Generally the combustible gases give out heat nearly in proportion to the oxygen they consume. See note at the end of Vol. 4, new series of the Manchester memoirs. ABSORPTION OF GASES BY WATER, &c.