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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1904 Excerpt:...of the calorific value a most laborious operation, but would also leave loopholes for so many sources of error that the results would be open to grave doubt. Given a good analysis, however, calculation enables one not only to obtain the calorific value under conditions where direct determination would be impossible, but also affords us an insight into the cause of any abnormal variation in thermal. value which might otherwise be diff1cult.to trace. Taking the calculation of the calorif1c value just given, it is clear that more than two-thirds of its heating power are due to the hydrocarbons present in it, and that methane is the factor which makes a good coal gas so superior to all other forms of gaseous fuel. The possibility of directly determining the calorific value of a combustible gas has only been placed within the reach of the gas manager during the past ten years by the introduction of that beautiful instrument that we all know as the Junkers calorimeter, and which has been so often brought before you as to need no fresh description from me. In this instrument, the heat generated by a flame is transmitted to water; measurement of the gas burned, and the volume and rise of temperature in the water giving all the data necessary to calculate the calorific value of the gas. The ease, rapid1ty, and accuracy with which determinations of thermal value in gases could be made by this apparatus have in reality created the possibility of a practical standard of heat value; and, as was to be expected, a rival calorimeter has appeared on the market in a modification of the Junkers apparatus, known as the Simmance-Abady calorimeter. I have frequently been asked as to the relative accuracy of the two forms of apparatus; and in order to provide an answer to the que...