426 ENGINEERING ON THE FARM 



carbureted with Blau-gas has a smaller range of explosibility 

 than any other known gas; that is, the proportions must be 

 in a very nearly constant quantity. Blau-gas is very high 

 in heating power — 1,800 British thermal units per cubic 

 foot — about three times as high as ordinary city illuminating 

 gas. It is put up in bottles containing 20 pounds, each 

 bottle yielding about 250 cubic feet of gas. 



The plant is a very simple one, consisting of a steel cabinet 

 with a capacity for two bottles of the liquefied gas, and a 

 reducing-valve and expansion tank. Standard gas pipe is 

 used through the house, and ordinary fixtures. It requires 

 a special burner for cooking. This gas gives the best results 

 when burned in a mantle. Since it is high in heating value, 

 it is used to some extent for brazing in small isolated plants, 

 such as garages, where small repair wonc is done. The 

 method or handling a Blau-gas plant is to return one bottle, 

 when emptied, to be exchanged for a full one, while the 

 second bottle is being used. 



Acetylene gas. Acetylene gas has been known on the 

 market for a long time. There are at present several very 

 satisfactory machines for producing and distributing this 

 gas. The raw material, or carbide, is produced in an elec- 

 tric furnace from ground coke and lime, thoroughly mixed 

 and burned together. It gives up its gas whenever it comes 

 in contact with water, or when exposed to moist air. It is, 

 therefore, imperative that the carbide be protected at all 

 times from air, as this gas is highly inflammable. Acetylene 

 gas ignites at a lower temperature than most gases, and is 

 not explosive at ordinary pressure when contained in a vessel. 

 It is, however, highly explosive when subjected to a pressure 

 of 150 pounds or more. This latter fact has been a source 

 of trouble to the manufacturers, but is now very satisfac- 

 torily overcome by the use of acetone in the compressing 

 process. The fact that acetone will absorb many times its 

 own volume of gas is taken advantage of; and, when so 

 absorbed, acetylene is practically non-explosive. The most 



