338 



♦ KNOW^LEDGE ♦ 



[September 1, 1SS6. 



fluted hearths, and a special arrangement for the entry of 

 fresh warmed air, as in " Doul ton's 8_vphon-action Ventilating 

 Tile Grate," radiate a maximum of pure heat into the room, 

 from an artistic and pleasing structure, with the only draw- 

 back attendant \ipon the nature of the material consumed, 

 viz., the necessity for frequent removal of ashes, and the 

 consequent dissemination of paiticles of dirt,* as well as of a 

 tendency to an escape into the room of occasional impurities 

 in the form of finely divided carbon (smoke and soot), car- 

 buretted and sulphuretted hydrogen, carbonic acid gas, and 

 water vapour ; but these drawbacks are comparatively 

 trivial when expense is taken into consideration. Not, 

 however, when a substitute in the form of a good stove is 

 provided, as such an appliance affords all the desirable 

 qualities of the open grate, save the cheerful aspect of the 

 ruddy blaze ; but then it has its drawbacks too, in the 

 accumulation of ash, dust and cinders, which, however, can 

 be minimised by the introduction of a suitable collecting 

 receptacle. Such are the qualities eadjoilied in Doulton's 

 really beautiful warming-stove. 



Mineral oils may be employed as fuel in place of solid 

 combustibles, but, as somebody has said somewhere, " they 

 are neither fish, flesh, fowl, nor yet good red-hening." 

 They do not warm the apartment equably throughout, and 

 are hence usually made portable, so as to be shilted about, 

 especially if the room happens to be moderately large. It is 

 true that they are cleanly, but that quality alone versus 

 ineflicient heating, cost of maintenance, the trouble of 

 constant shifting and its inseparable concomitant the 

 impoverishment of the atmosphere through combustion, 

 deservedly dwindles into insignificance. A feeble attempt 

 to imitate the " cheerful blaze" of a coal fire is sometimes 

 made in the shape of an ingeniously-airanged metallic 

 reflector and panes of ruby-coloured glass. They are 

 useful, however, for very small laboratories, such as many 

 a private student of nature can ])revail upon the tender- 

 hearted housewife to abandon to him, and the best pattern 

 in the market is, without doubt, that of the " Albion Lamp 

 ]\ranufacturing Company," Messrs. Rippingille & Company, 

 of Birmingham. 



Lastly, coal gas may be used as fuel, and here, apart from 

 costliness, is to be found the student's desideratum. A gas 

 fire can be arranged to provide a cheery flame ; all the jiro- 

 ducts of combustion are most easily removed, fresh warmed 

 air can be as readilj' admitted, and lateral chambers can be 

 added wherein to do the " cookery of science ; " there is no 

 dirt to bo removed, with practically no attention to be 

 l)estowed upon the maintenance, nay, the accurate regula- 

 tion, of the warmth in the laboratory ; but, alas ! all of these 

 advantages are only too often overbalanced by the state of 

 the poor naturalist's exchequer. The name of Fletcher is 

 inseparable from this subject on account of the many forms 

 of heiiting apparatus which he has invented, and which so 

 justly entitled him to the celebrity he enjoys. 



The artificial lighting of the laboratory is not to be com- 

 mended for careful work, elaborate dissections-, observing 

 with the microscope, or in delineating objects. One hour's 

 devotion during the daylight with the clear light reflected 

 from cumular clouds or a bright blue sky is, according to 

 the experience of the majority of persons, positively de- 

 lightful in contradistinction to the feeling akin to pain 

 engendered by even a few minutes of study witli the aid of 

 unnaccustomed, and, iryo, unnatural light. Still, there are 

 many cases in which a steady clear lamp or gas flame is 

 al)le to afford results which cannot so well be attained by 

 daylight ; for instance, as in researches respecting the true 



* The term " dirt " here must be understood to signify "matter 

 ill the wrong place." 



nature of natural diffraction gratings, e.g., the tests of 

 diatomaceous plants, Pleurositjnia o'ligvlatum, Amphipleiira 

 pellucida ; kc, in continuous investigations into the optical 

 qualities of amplification and resolution in relation to the 

 angular aperture of lenses, the study of the life-history of 

 such minute creatures as Monads, kc, all of which make it 

 necessary for the student to employ an unfiiling, pre- 

 directed, and uninteiinipted source of light. But these opera- 

 tions are immediately without the limits of this paper, and 

 are only rarely followed by special enthusiasts — Mr. Nelson, 

 Professor Dallinger, Dr. Abbe, and others, whose untiring 

 energy can alone supply them with the necessai'y " ins and 

 outs" to enable them to prosecute their inquiries with 

 success. 



Still, artificial lighting must not be wholly neglected, as 

 it may often be used with great advantage. For occasional 

 work, for displays, and for literary labour, the "midnight 

 oil " will always be welcomed, and, from the nature of the 

 manipulator's occupations, a steady, clear, portahh light 

 must obviously be the best, so that the employment of 

 mineral oils which have long since superseded animal 

 and vegetable oils, both as regards economy and efficiency, 

 must be preferred to gases as illuminants. The reason for 

 this choice is that, although coal gas has during the past 

 decade been so improved upon that " the amount of sulphur 

 around a gas-burner x^, at least in London, less than half 

 what it was a few years ago, there is still, however, a 

 step in advance to be taken, eight or ten grains of 

 sulphur in every 100 cubic feet of gas still to be removed, 

 before gas can claim to be in this respect as perfect a domestic 

 illuminant as candles or oil." * As regards mineral oils, 

 where snch are used as heat-givers in addition to their 

 illuminative function, Mr. (ieorge J. Snelus says f : — "One 

 difficulty connected with their use for this purpose is that 

 imperfect combustion gives rise to very unpleasant odours ; 

 but where combustion is perfect, as in a good Hinks, Siiber, 

 or Mitrailleuse lamp, considerable heat as well as light may 

 be obtained at a very small expense, and in a very convenient 

 way. The products of combustion, however, should, if 

 possible, be carried oft" by special arrangement when large 

 burners are used, although, from their freedom from sulphur, 

 they are not nearly so deleterious as those of gas." 



A few observations upon the construction and uses of 

 mineial oil lamps may therefore be noted in this place for 

 the benefit of the student. Captain Shaw's report for 1881: 

 shows that, of the known causes of fires in London, one- 

 fifth can be traced to the overturning or explosion ol 

 mineral lamps, as the nature of the volatile liquid is antago- 

 nistic to its being heated or exposed to the open air in the 

 presence of flame. Although the flame of a mineral oil 

 lamp cannot be super-heated and its illuminating power 

 increased by being fed with heated air, as in many forms of 

 the gas flame, its careful construction is capable of being so 

 highly utilised that in one lamp called the " Defries' 

 Safety Lamp " (Sepulchre's patent), an average illuminating 

 power of 52-14 standard candlest has been registered by a 

 series of careful photometric tests. The lamp is constructed 

 with but a single wick, and, when its candle-power is taken 

 into consideration, it burns less oil than any other lamp yet 

 introduced. Mr. Eoverton Redwood's report upon the' 

 lamp gives a good idea of the esi-ential requirements of a 

 thoroughly efficient appliance. He says : — '■ The con- 

 struction of this lamp is such that neither ignition 



* Dr. A. Yernon-Harcourt, Official Catalogue of the International 

 Inventions Exhibition, London, 188.5, p. 171. 



f " Fuel, Furnaces, etc.," Official Catalogue of the International 

 Inventions Exhibition, London, 1885, p. 18t. 



J " A sperm candle of .six to the pound, burning one hundred 

 and twenty grains an hour.'' Cf. the metropolis Gas Act, 1860. 



