THE USE OF ACETYLENE. 343 



gas. The odor of acetylene is unpleasant; so is the odor of the water 

 gas used generally in the United States, and the acetylene can be 

 cheaply deodorized. 



As the generator system, then, is the general one, the most impor- 

 tant question to the consumer is what generator to buy, and it is a 

 perplexing question. The carbide manufacture is so organized that 

 it is everywhere under the control of powerful and responsible com- 

 panies which sell a guaranteed product. The burners now in use 

 are nearly all good. With generators it is different; the market is 

 flooded with them at all prices, ranging in value from worse than 

 useless to very good, as regards safety, economy, and quality of light. 

 As the generator question is by far the most important and the least 

 understood in the whole acetylene industry, it will be well to give a 

 full account of the results of the experiments which have been made 

 within the last two years on this question. The most exhaustive 

 experiments are those of the English expert, Professor Lewes, and 

 his results agree with those of other observers. 



Lewes first determined the amount of heat developed by the de- 

 composition of carbide by water, and the conditions which tend to 

 lessen or increase the intensity of the reaction. The average result 

 of the experiments as to the amount of heat was 446.6 calories for 

 pure carbide, and a little less for commercial carbide (to state this 

 differently, one pound of carbide, when decomposed by water, gives 

 off heat enough to raise the temperature of 446.6 pounds of water 1 

 0., or to raise the temperature of one pound of water 446.6 C.). As 

 the intensity of the heat developed determines the highest tempera- 

 ture attained during the decomposition, and is a function of the time 

 needed to complete the action, and as the decomposition of carbide 

 in contact with water is extremely rapid, it is evident that the tem- 

 perature developed may be so high as to cause disaster. All the gen- 

 erators at present before the public may be classified under three 

 heads: 1. Those in which water is allowed to drip or flow slowly on 

 a inass of carbide, the evolution of the gas being regulated by the stop- 

 ping of the water. 2. Those in which water in considerable volume 

 is allowed to rise in contact with carbide, the evolution of the gas be- 

 ing regulated by the driving back of the water by the increase of pres- 

 sure in the generating chamber. 3. Those in which the carbide is 

 dropped or plunged into an excess of water. 



The conclusions deduced from a large number of experiments 

 were that when, as in type 1, water is allowed to drip or flow in a fine 

 stream upon a mass of carbide, the temperature rapidly rises until 

 after eighteen to twenty-five minutes the maximum is reached, which 

 varies from 400 to 700 C. (720 to 1120 Fahrenheit), and it is 

 probable that in some of the mass the higher limit is always reached, 



