Both chemists and brewers would gladly welcome some method of testing hops, which should be expeditious, and afford reliable results in practical hands. To accomplish this account must be taken of all the active organic constituents of the hops, which can be extracted either with ether, alcohol, or water containing soda (for the conversion of the hop tannin in phlobaphen).[1] It should further be ascertained whether the chlorophyl percentage in the hop bells, new and old, is or is not the same in cultivated and in wild hops, and whether the aggregate percentages of organic and constituent observe the same limits. [Footnote 1: See C. Etti, in "Dingler's Polytech. Journ.," 1878, p. 354.] As wild hops nowadays are frequently introduced in brewing, the proportion of chlorophyl and organic and inorganic constituents in them should be compared with those of cultivated sorts, taking the best Bavarian or Bohemian hops as the standard of measurement. The chlorophyl is of minor importance, as it has little effect on the general results. By a series of comparative analysis of cultivated and wild hops, in which I would lay especial stress on parity of conditions in regard of age and vegetation, the extreme limits of variation of which their active organic principles are susceptible could be determined. There is every reason to suppose that the chlorophyl and inorganic constituents do not differ materially in the most widely different sorts of hops. The more important differences lie in the proportions of hop resin and tannin. When this is decided, the proportion of tannin or phlobaphen in the hop extract or the beer can be determined by analysis in the ordinary way. But whenever some quick and sure hop test shall have been found, _appearance and aroma_ will still be most important factors in any estimate of the value of hops. Here a question arises as to whether hops from a warm or even a steppe climate, like that of South Russia, contain the same proportion of ethereal oil--that is, of aroma--as those from a cooler climate, like Bavaria and Bohemia, or like certain other fruit species of southern growth, they are early in maturing, prolific, large in size, and abounding in farina, but _deficient in aroma_. The bearings of certain experimental data on this point I reserve for consideration upon a future occasion.--_The Analyst_. * * * * * WATER GAS. A DESCRIPTION OF APPARATUS FOR PRODUCING CHEAP GAS, AND SOME NOTES ON THE ECONOMICAL EFFECT OF USING SUCH GAS WITH GAS MOTORS, ETC. [Footnote: Abstract of paper read in Section G. British Association, York] By MR. J. EMERSON DOWSON, C.E., of London.