304 



NATURE 



[January 24, 1895 



peratnre of the arc, fased down to a heavy semi-metallic mass, 

 which having been examined, and found not to be the substance 

 sought, was thrown into a bucket containing water, with the 

 result that violent effervescence of the water marked the rapid 

 evolution of a gas, the overwhelming odour of which enforced 

 attention to its presence, and which, on the application of a 

 light, burnt with a smoky, but luminous flame. 



Investigation into the cause of this pheno nenon soon showed 

 that in a propeily constructed electric furnace, finely ground up 

 chalk or lime, mixed with powdered carbon in any form, 

 whether it were charcoal, anthracite, coke, coal, or graphite, 

 can be fused with the formation of a compound known as calcic 

 carbide, containing 40 parts by weight of the element calcium, 

 the basis of lime, and 24 parts by weight of carbon, and that, 

 on the addition to this of water, a double decompositiori takes 

 place, the oxygen of the water combining with the calcium of 

 the calcic carbide to form calcic oxide or lime, whilst the 

 hydrogen unites with the carbon of the calcic carbide to form 

 acetylene, the cost of the gas so produced bringing it not only 

 within the range of commercial possil>ijties for \ix per se, but 

 also the building up from it of a host of oiher compounds, whilst 

 the production of the calcic carbide from chalk and from any 

 form of carbon, renders us practically independent of coal and 

 oil, and places in our hands the prime factor by which nature 

 in all probability produces those great underground storehouses 

 of liquid fuel upon which the world is so largely drawing 

 to-day. 



Calcic carbide is a dark grey substance, having a specific 

 gravity of 2262, and, when pure, a pound of it will yield on de- 

 composition 53 cubic feet of acetylene. Unless, however, it is 

 quite fresh, or means have been taken to carefully protect it 

 from air, the outer surface gets slightly acted upon by atmo- 

 spheric moisture, so that in practice the yield would not exceed 

 five cubic feet. The density and hardness of the mass, how- 

 ever, protects it to a great extent from atmospheric action, so 

 that in lumps it does not deteriorate as fast as would be ex- 

 pected, but in the powdered condition it is rapidly aciedupoii. 



The acetylene made from it, when analysed by absorption with 

 bromine, the analysis being also checked by determining the 

 amount present by precipitation of silver acetylide, gives 98 per 

 cent, of acetylene and 2 per cent, of air, and traces of sul- 

 phuretted hydrogen, the presence of this impurity being due to 

 traces of sulphate of lime— gypsum — in the chalk used for 

 making it, and to pyrites in the coal employed. 



Aceiylene is a clear, colourless gas with an intensely pene- 

 trating odour which somewhat re-embles garlic, its strong smell 

 being a very great safeguard in its use, as the smallest leakage 

 would be at once detected ; indeed, so pungent is this odour, 

 that it would be practically impossible to go into a room which 

 contained any dangerous quantity of the gas. 



Thi> is an important point 10 remember, as the researches of 

 Bistrow and Liebreich show that the gas is poisonous, 

 combining with the bxmoglobin of the blood to form 

 a compound similar to that produced by carbon monoxide : 

 whilst the great danger of ihe latter gas is that having no 

 smell, in presence is not delected until symptoms of poisoning 

 begin to show themselves, so that no fear need be apprehended 

 of danger from this source with acetylene. 



Acetylene is soluble in water and most other liquids, and at 

 ordinary temperature and pre-sure— 60 F. and 30 inches 

 of mercury — 10 volumes of water will absorb 1 1 volumes of the 

 gu ; but as soon as the gas is dissolved, the water being 

 saturated i.ike« up no more. Water already saturated with 

 cr,r . acetylene quite so rea lily, whilst Ihe 



gn ■■ in s.iuiratcd brine — loc volumes of a 



saiuiu.c. ... nly dissolving 5 volumes of the gas. 



The gas is far more soluble in alcohol, which at normal 

 tempt r.iture and prcsuic takes up six times its own volume of 

 Ihe acetylene, whilst 10 volumes of paraffin under the same 

 conditions will ab«orb 26 volumes of the gas. It is a heavy 

 ga«, having n specific gravity of 0-91. 



When a light is applied to ac'l>lcne, it burns with a luminous 

 and intensely sm >ky llame, and when a mixture of one volume 

 ol acetylene with one volume of air is ignited in a cylinder, 

 a dull red (lame run* down the cylinder, leaving be- 

 hind a mass of tool, and throwing out a dense black 

 imoke. When aceiylene is mixed with 1-25 times its own 

 volume of air, the mixture Iwgins to be slightly explosive, the 

 explosive violence increasing until it reaches a maximum with 



NO. 1317. VOL. 51] 



about twelve times its volume of air, and gradually decreases in 

 violence until, with a mixture of one volume of acetylene to 

 twenty of air, it ceases to be explosive. 



The gas can be condensed to a liquid by pressure, Andsell 

 finding that it liquefied at a pressure of 21 5 atmospheres, at a 

 temperature of o* C, whilst Cailletet found that at l' C. it re- 

 quired pressure of 48 atmospheres, the first-named pressure 

 being probably about the correct one. The liquid so produced 

 is mobile, and highly refractive, and when sprayed into air, the 

 conversion of Ihe liquid into the gaseous condition absorbs so 

 much heat that some of the escaping liquid is converted into a 

 snow like solid, which cntches fire on applying a light to it, 

 and burns until the solid is all converted into g.is and is 

 consumed. 



In my researches upon the luminosity of flame, I have shown 

 that all the hydrocarbons present in coal-g.is and other luminous 

 flames are converted by the baking action t.iking place in 

 the inner non-luminous zone of the flame into acetylene before 

 any luminosity is produced, and that it is the acetylene which 

 by its rapid decomposition at 1200' C. provides the luminous 

 flame with these carbon particles, which, being heated to 

 incandescence by various causes, endow the flame with the 

 power of emitting light The acetylene, being in this way 

 proved to be the cause of luminosity, one would expect that in 

 this gas we have the most powerful of the g.iseous hydrocarbon 

 illuminants ; and experiment at once shows that this is the 

 case. 



Owing to its intense richness, it can only be consumed in 

 small flat flame burners, but under these conditions emits a light 

 greater than that given by any other known gas, its illuminating 

 value calculated to a consumption of 5 cubic feet an hour being 

 no less than 240 candles. 



flluminalin^ Power of Hydrocarbons for a Consumption of 

 5 cubic feet of Gas. 



Candles. 



Methane S'2 



Ethane 357 



Propane 5^7 



Ethylene 7oo 



Butylene 123'° 



.\cetylene 240-0 



It is stated that the carbide can be made at about £^ a ton ; 

 and if this be so, it should have a great future, as a ton will 

 yield 11, coo cubic feet of the gas. The lime left as a bye- 

 product would be worth los. a ton, and the gas would cost at 

 this rate bs. ^\ii. per 1000 cubic feet, and in illumintiting 

 value would be equal to London coal gas at dJ. a thousand. 

 Its easy production would make it available for illuminating 

 purposes in country houses, whilst its high illuminating v.ilue 

 should make it useful for enriching poor c0.1l gas. 



CHEMICAL CHANGES BETWEEN SEA- 

 WATER AND OCEANIC DEPOSITS.' 

 THEnumerous.analysesofsea water by Forchhammer previous 

 to 18(15, and the later analyses by Dilimar, from samples 

 collected during the Challenger Expedition, show that while 

 the salinity— i.e. the amount ol dissolved salts contained in 100 

 parts of sea-water— varies greatly in difl'erent regions of the 

 ocean, still the composition of these dissolved sails— /.c. Ihe 

 ratio of the constituents of sea-salts— remains practically Ihe 

 same in all the superficial waters of the ocean. Consequently, 

 it is only necessary to dclermine the chlorine in a dclinite 

 weight ol water to ascertain at once the respective quantities of 

 the other salts present in the sample. Ditlmar's examination 

 of the Challenger waters has, however, shown that lime is 

 slightly, alihough distinctly, more abundant in samples of sea- 

 water collected in greater depths than in those samples collected 

 nearer the surface of the ocean, and Diit mar's tables showing the 

 difference between the chlorine calculated from the specific 

 gravity and the chlorine found by analysis - point to difl'erences 

 in Ihe composition of the sea-salts ; but Ihe observations are 



1 Abstract of a I'aptr rf.-.d hcforr. ll.r Roy.ll Society of Edinburjth on 

 Marctl 7. 1693. by Dr. John Murray and Robcrl Irvrne, and published 

 in Trail's., vol. xxxvii. pan a, No. 33. _ „ 



" Dittmar, "Clintlengtr Keporl on ihe Composilion of Ocean W.iter, 

 " Phys.Chem Clinit Exp , "pan 1. p. 41- 



