British Thermal Unit - Combustion of Carbon, Acetylene, Hydrogen, and Coal Gas - Coefficient of Heat - Consumption of Combustible Gases - Pressure, Weight, and Volume of Air - Temperature of Fusion, Metric and English Measures.

British Thermal Unit is the amount of heat required to raise the temperature of 1 lb. of water at 32° Fahr. 1° Fahr.

On the continent of Europe the caloric is used, and the standard is the heat required to raise the temperature of one kilogramme of water one degree Centigrade.

To convert British thermal units per pound of coal into calories per kilogramme of coal, multiply by 5 and divide by 9.

Combustion of 1 lb. of carbon requires 2.66 lb. oxygen, and as the atmospheric air contains only 23 per cent. of oxygen, it follows that 11.6 lbs. of air are necessary for the combustion of 1 lb. of carbon.

One volume of acetylene requires theoretically 2 1/2 volumes of oxygen for complete combustion, but with a satisfactory blowpipe the best welding results are obtained with 1.7 volumes of oxygen to one volume of acetylene.

Two volumes of hydrogen require one volume of oxygen for complete combustion, but in order to ensure a non-oxidising flame the gases must be burned in the proportion of about four volumes of hydrogen to one volume of oxygen.

One volume of coal-gas requires about 1.25 volume of oxygen for combustion, but for general purposes about 1.33 volume of oxygen is used.

Coefficient of Heat.

Combustible Gases.

The consumption of liquefied and compressed gases during 1906 is given as follows: -

It is interesting to note the steady and enormous increase in the consumption of liquefied and compressed gases in Germany, given as follows : -

Such an enormous annual increase in the production of liquefied and compressed gases, and their subsequent application for industrial purposes, as already indicated, is a proof so complete that the nature of enquiry cannot be touched by criticism; nevertheless, there is still room for improvement and for new fields to be found for their practical application.

Pressure.

One Atmosphere = 14.7 lbs. per square inch = 2116.35 lbs. per square foot; = 33.90 feet of water; = 1.033 kilogrammes per square centimetre = 760 m.m. of mercury.

Weight and Volume of Air.

A cubic foot of air at 60° and under average atmospheric pressure, at sea level, weighs 536 grains; and 13.06 cubic feet weigh 1 lb.

Air expands or contracts an equal amount with each degree of variation in temperature.

Temperature of Fusion.

Tin, 455°; bismuth, 518°; lead, 610°; aluminium, 850°; zinc, 700°; antimony, 810°; brass, 1,650°; silver, pure, 1,830°; gold coin, 2,156°; iron, cast, 2,010°; steel, 2,250°; and wrought iron, 2,910° Fahr.

Conversion.

Fahrenheit = 5/9 Centigrade + 32).

5 Centigrade = 5/9 (Fahrenheit - 32).

Metric and English Measures, as Compiled and Published by P. E. Radley.

Reciprocals for Rapid Approximate Calculations.