360 



NA TURE 



iFeb. 17, 1 88 1 



Dr. Agardh does not admit them among the Floridea; ; 

 and in Dr. A. W. Bennett's new scheme for the classifica- 

 tion of the lower cr\-ptogams,' they seem to be literally 

 nowhere. Neither has Dr. Bennett assigned any place in 

 his scheme to the rather extensive family Valoniese. It 

 is to be hoped that algologists will agree before long on 

 the position which these forms are finally to occupy in 

 the classification of Algse. 



His work on the Florideae having been thus brought to 

 a successful termination, it is to be hoped that Dr. Agardh 

 will now turn his attention to the Melanosperms, and that 

 he will, before long, give us a new edition of the first 

 volume of his "Species Algarum"; a w'ork rendered 

 necessaiy by an increased knowledge of the structure and 

 fructification of these plants, and by the discovery and 

 accurate examination of many new species. The ex- 

 professor has already revised and reconstructed the 

 extensive genera Laminaria, Zonaria, Funis, Cysto- 

 phora, and Sargassum — the latter as far as relates to 

 the Australian species of the sections Ptcfocaulon and 

 A7-ilnophyciis only. To these must be added descriptions 

 of many new species of Melanosperms, all of which have 

 been published in the Proceedi7igs of the Swedish Acade- 

 mies, and are, therefore, not within reach of many who 

 would gladly consult them. A new edition, in which 

 these scattered papers shall be collected and classified, 

 would be a boon to algologists, and, we trust, would not 

 entail very great labour upon the learned and industrious 

 author. M. P. M. 



LETTERS TO THE EDITOR 

 \The Editor does not hold himself responsible for opinions expressed 

 by his correspondtnts. Neither eaii he undertake to return^ or 

 to correspond with the writers of, rejected manuscripts. No 

 notice is taken of anonymous covimunications. 

 T7i£ Editor urgently requests correspondents to keep their letters as 

 short as possible. The pressure on his space is so great that it 

 is impossible otherwise to ensure the appearance even of com- 

 niunicatiotis containing interesting and novel fcuts^ 

 "The New Cure for Smoke" 



Nature, vol. xxiii. p. 25, contains a letter from Dr. Siemens 

 on a "new cure for smoke," and in that letter it is stated that, 

 instead of using inert matter such as pumice-stone, he (Dr. 

 Siemen>) considers it far more economical and efficacious, in a 

 gas-grate to transfer the heat of the gas-flames to gas-coke or 

 anthracite, and that the result obtained shows that the "coke- 

 gas fire " is not only warmer, but cheaper than its predecessor, the 

 coal-fire, with the advantage in its favour that it is thoroughly 

 smokeless. 



Nou having had considerable experience with gas-heating 

 fires of various kinds, and being mucli interested in the success 

 thereof, I determined to give the "gas-coke grate" a practical 

 trial ; and as the re-ult of the trials which I have just completed, 

 and which extended over a period of two months, may interest 

 many of your readers, possibly you may be able to find space 

 in your cohimi.s to record the following particulars : — 



In the fir,-.t set of trials a good modern fire-grate was arranged 

 (as described by Dr. Siemens) with a solid iron dead-plate, and 

 J-inch ga-i-i)ipe, pierced \vith holes ^nrth of an inch in diameter, 

 placed in the front part of the grate, but behind the lowest b.ir, 

 and all air excluded from below except that which was allowed 

 to pass in between the hollow bottom and enter on the line of 

 gas flames. The grate was then filled with coke broken into 

 pieces about the size of a large walnut, the gas turned on and 

 lighted. In a short time a good bright fire with a rich flame was 

 obtained; the external temperature at starting was 32° F., and 

 that of the room 45° F. This latter rose within two hours to 

 62° F., and was maintained as long as the fuel lasted, viz. fifteen 

 hours, the gas and coke burning brightly die whole time. 



' See the Report in Nature (vol. xxii. p. 451) of a paper read before the 

 British Association at Swansea last year. 



The result of a number of these trials, with an expenditure of 

 28 lbs. of coke, was an average consumption of 325 cubic feet of 

 gas, the expenditure of the latter being very accurately ascer- 

 tained by passing the gas through a standard test meter. 



A second set of trials was then made under conditions pre- 

 cisely similar to the above, with the exception that the gas was 

 used only for lighting the coke at the commencement, and when 

 a good fire was obtained, and the temperature had risen to 62° F., 

 it was turned off, and only used again for a short time to rein- 

 vigorate the fire and maintain the temperature. This second 

 series of trials — with an expenditure of 28 lbs. of coke — resulted 

 in an average con-umption of fifty cubic feet of gas ; the fire, 

 w hen the gas was turned off', was not so bria;ht or rich as in the 

 first series, and the fuel only lasted thirteen hours. 



Upon the completion of the coke and gas trials as above, the 

 grate was restored to its original condition for burning coal. 

 The fire was lighted in the usual manner, and within two hours 

 the temperature rose to 62° F. as in the previous trials, the 

 external tempenature at starting being 32° F. , and that of the 

 room 45° F., and with a consumption of 28 lbs. of coal 62° F. 

 was maintained for fourteen hours. 



The room in which the experiments were made was the same 

 in each case, having a capacity of about 3000 cubic feet, a due 

 north aspect, and situated about 150 yards from the river, to 

 which it is entirely open. 



Tlie above facts having been ascertained after an extended 

 and repeated series of trials, in which ' the fuel was most care- 

 fully weighed and the gas measured, it now becomes a simple 

 matter to reduce the results to £ s. d., and in doing so I have 

 taken the present prices of gas, coke, and coal in this neighbour- 

 hood, which are as follows : — Coal, 26s. per ton ; coke, 12s. per 

 chaldron ; and gas, 3,r. Tid. per thousand cubic feet. From these 

 we obtain the undermentioned results, viz. : — 



First Trials. Coke and Gas continuously for fifteen hours 



d. 

 28 lbs. of coke at I2J-. per chaldron 2"57i 



325 cubic feet of gas at 3^. %d. per 1000 cubic feet 12 '675 



15-246 

 Or i'oi64 pence per hour. 



Second Trials. Coke, with Gas for lighting and use occasionally 

 for assisting the Coke, for thirteen hours 



d. 



28 lbs. of coke at 1 2j. per chaldron 2'57i 



50 cubic feet of gas at '^. yi. per 1000 cubic feet i '950 



Or '3477 of a penny per hour. 



Third Trial. Coal only, for fourteen hours 



d. 



28 lbs. of coal at 26i. per ton 3 '9 



Or "2785 of a penny per hoirr. 



It ■« ill, I think, be at once seen from the foregoing results that 

 although by the use of gas and coke we get rid of the smoke 

 nuisance, that desirable end is not obtained entirely without cost, 

 and that, judging from these experiments, the "coke gas fire," 

 while possessing many of the advantages claimed for it, has not 

 proved in this instance to be warmer and cheaper than its 

 predecessor the "coal fire." 



Possibly some of your professional readers may find time to 

 pursue the subject further and favour us with the result of their 

 investigations. I have given a good deal of attention for years 

 past to the employment of gaseous fuels, and have made many 

 experiments, but I do not at the present time know of any fire- 

 grate or stove (for ordinary household purposes) wherein gas is 

 employed as the heating agent, either wholly or in part, which 

 gives such good results as the raw material coal. At the same 

 time there can be little doubt but that we shall yet discover the 

 way to eflfect great economy in the use of fuel both for domestic 

 and manufacturing purposes, and ultimately to solve the smoke 

 nuisance question ; but whether it will be by separating the raw 

 material into its several constituents and bringing some of them 

 together again under different conditions and proportions when 

 being consumed in a gas furnace or grate, or by better and more 

 perfect appliances for effectually burning the fuel in its raw state, 

 Uas, I think, yet to be settled. The question however is one 

 which concerns all alike, being a matter of both personal and 

 national mterest. J. A. C. Hay 



Royal Arsenal, Woolwich, January 29 



