SCIENCE-GOSSIP. 



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during certain chemical combinations. Its scent 

 may have been observed, on the coal-gas being 

 turned off, by those persons who have used a 

 Bunsen burner. As early as 1836, Edmund Davy, 

 Chemical Professor to the Royal Dublin Society, 

 discovered and described acetylene gas, speaking 

 •of it as a " gaseous bicarburet of hydrogen and of 

 a particular compound of carbon and potassium " 

 (British Association Reports, 1836, pt. 2, p. 62). 

 Later, in 1861, a German chemist, named Wohler, 

 made experiments in calcium carbide, but it was 

 not until M. Berthelot's researches, extending 

 over several years, that anything definite was 

 known as to the composition of this gas. This 

 eminent chemist, in 1866, obtained acetylene 

 by passing hydrogen through a receiver, which 

 had an electric arc maintained between carbon 

 electrodes. He also showed that the decomposition 

 by heat of many organic substances would produce 

 acetylene in small quantities. It was not, however, 

 realized that this gas had any commercial value, 

 until the Moissan incident drew attention to the 

 fact. It had been looked upon by chemists as 

 merely a scientific curiosity, and as rather a 

 nuisance than otherwise. After M. Henri 

 Moissan's experiment, several British patents 

 were applied for, one being for Mr. Thomas L. 

 Willson, a Canadian chemist living in the 

 United States of America. His application was 

 received at the Patent Office in England on 

 February 28th, 1894, being antedated by six 

 months under the International Convention on 

 Patent Laws. There being an error in the ante- 

 dating, a private Bill was presented to the Imperial 

 Parliament for its rectification, and became a mat- 

 ter of discussion before a Committee of the House 

 of Lords in March, iSg6,when the Preamble of the 

 Bill was not proved and the Bill consequently did 

 not become an Act. 



Considering the recent progress which has been 

 made towards a knowledge of liquefying gases by 

 placing them under immense pressure, it is not 

 surprising that efforts have been made to condense 

 acetylene in like manner. This has, unfortunately, 

 led to several serious accidents, and some loss of 

 life, and has resulted in an unnecessary suspicion 

 being aroused among the uninitiated as to this gas 

 being more dangerous than coal-gas. 



MM. Berthelot and Vielle, however, have made 

 some very valuable investigations regarding the 

 explosion of liquefied acetylene, and it will doubt- 

 less be interesting to many people to learn, as 

 pointed out by Professor Vivian Lewes, in his 

 lectures at the Society of Arts at the end of last 

 year, that they found a cylinder filled with liquefied 

 acetylene did not explode when dropped repeatedly 

 from nearly twenty feet upon a large steel anvil, 

 but if the cylinder was crushed the impact 

 was shortly followed by an explosion, this being 



due to the escaping gas mixing with the air and 

 becoming ignited from sparks caused by the break- 

 ing of the vessel. At present, however, acetylene 

 gas is not commercially made of such purity that it 

 will bear liquefaction, or even considerable com- 

 pression, without being liable to explosion, as 

 are other gases under similar conditions. It is 

 probable that the impurities which cause this 

 liability arise from the phosphates contained in the 

 lime used for the production of carbide. For 

 lighting purposes, however, it is an actual dis- 

 advantage to place acetylene under high pressure, 

 the danger of explosion, therefore, from this 

 source absolutely disappears. In practice it is 

 not necessary to use more than a couple of 

 ounces or so pressure per square inch, while the 

 Board of Trade Orders in Council fix in this 

 country the highest limit at a pressure equal to a 

 column of water 100 inches in height, that is to say, 

 at about seventeen pounds to the square inch. 



It is becoming recognized that there is little or 

 no saving for the purposes of transport in placing 

 this gas under pressure at all. This is because the 

 best carbide produces so much gas that the residue 

 of lime left after its decomposition is less in weight 

 than would be the heavy iron vessels necessary to 

 convey the compressed gas. It will therefore be 

 seen that the dry carbide containing the undis- 

 charged gas is no more inconvenient to carry than 

 would be the iron "bottles" of compressed gas, 

 and needs no return for refilling. In the case of 

 carbide its transportation is absolutely safe when 

 packed in sealed tins. 



Carbide in appearance resembles a dark grey 

 crystalline stone ; it is very hard, and not easy to 

 break into small pieces without the aid of a heavy 

 hammer with sufficient crushing power. When 

 broken, the pieces are not unlike some varieties 

 of macadam stone. The material is strong-smell- 

 ing if the atmosphere is in the least damp. If, 

 however, it could be placed in a perfectly dry 

 surrounding, no scent would be evolved, as the 

 smell is the result of minute quantities of acetylene 

 gas given off by the action of the water in the 

 atmosphere. For commercial purposes the carbide 

 is stored and sent out in tightly-fitting tin canisters 

 of required sizes. 



To generate this gas for illuminating purposes 

 several forms of instruments have been designed. 

 They have received by common consent the appel- 

 lation of " generators." The best systems consist 

 of a receiver in which water is placed, regulated 

 with a floating ball-tap. Into this water is 

 put a gasometer, which rises and falls, as do the 

 ordinary huge gasometers at our coal-gas works. 

 Three systems have come into operation in 

 generating acetylene gas, and they may be 

 considered as advantageous in the following 

 sequence : (1) Where the carbide is dropped 



