82G TRANSACTIONS OF SECTION G. 



gas should he clean, of good quality, and of uniform pressure. This is especially 

 necessary where the gas must be burnt with air at pressure, as for blow-pipes, &c. 

 Producer gas is now used for the following as well as many other purposes : 

 Cooking and baking in hospitals and asylums, japanning and enamelling, type- 

 founding, varnish making, melting in crucibles, cutting and finishing glass, 

 heating tailors' irons in clothing factories, and laundry irons, calenders, &c., 

 gassing silk and cotton yarns, singeing textile fabrics, soldering biscuit and 

 condensed-milk tins, &c., annealing, hardening and tempering, boiling sugar, 

 roasting coR'ee, cocoa, and other food-products in factories. Notwithstanding this 

 the author considers that, in proportion to the immense amount of heating 

 required in the various industries throughout the Kingdom, more progress would 

 have been made if manufacturers and others knew more about the subject 

 technically. Often they do not seem to understand the treatment of gas, or 

 what can be done with it. Undoubtedly the greatest development in the use of 

 producer gas has been with gas engines. A gas engine was worked for the first 

 time with producer gas in 1879, in a plant devised by the author. The calorific 

 power of producer gas is the same now as then, but less gas is now consumed per 

 h.p., owing to improvements made in the engines. The meaning of pressure and 

 suction gas was described. In 1862 Dr. Jacques Arbos of Barcelona patented 

 a gas producer worked by the suction of an engine, but the first to deal with this 

 in a practical way was M. Leon Bt^nier of Paris (1891"). Various modifications 

 and improvements have since been made, and the suction plant is extensively 

 used. The chemical reactions on which pressure and suction gases depend are 

 identical, but the calorific power of pressure gas made with a jet of superheated 

 steam is usually considerably higher than that of suction gas. For heating 

 purposes in small burners, or in blowpipes, pressure gas is better, and an engine 

 worked by suction gas develops a rather lower maximum power than with pres- 

 sure gas. In considering the two types of plant for engine work, the general 

 conclusions are : A suction plant costs less and occupies less ground space, but 

 the gas made in it is not so strong as in the older form of pressure plant, and in 

 some cases this is important. The fuel consumption per h.p.-hour and the labour 

 required are the same in both types of plant, provided the steam required for 

 the pressure gas is raised without an independent boiler. The consumption of 

 water is the same in both types. Where there are several engines to serve, the 

 gas piping is simplified and its cost reduced when the gas is taken from a small 

 gasholder, instead of from several suction plants. In some cases the pressure type 

 is better than the suction, in others suction is better than pressure. From the 

 economical point of view, where producer gas is used for heating work instead of 

 ordinary town gas, there is usually a saving of 50 to GO per cent. With engines 

 the consumption of aiithracite is guaranteed not to exceed 1 lb. per b.h.p.-hour 

 (under full or three-quarter loads) in both types of plant. Gas coke is also used, 

 but its consumption is a little higher. For large furnace work non-caking 

 bituminous coal is almost invariably used, and in some cases this kind of coal is 

 also used for engine work. 



3. Suction Gas Producers.^ By P. W. Robson. 



4. The Study of Breakages."^ By Waltkr Rosenhain, B.A., B.C.E. 



The importance of the thorough investigation of failures or breakages occur- 

 ring in engineering practice was dwelt upon in the first part of the paper, more 

 particularly on the ground that such cases serve to show where our existing 

 knowledge and experience are at fault. Manufacturers of materials of engineer- 

 ing construction sometimes shrink from full investigation of failures, but it is 

 frequently found that the failure arose from causes other than inherently bad 



' Published in Etigineering, September 11. * Jhid, 



