August iq, 1922] 



NA TURE 



A Recording and Integrating Gas Calorimeter. 



By Dr. J. S. G. Thomas, Senior Physicist, South Metropolitan Gas Company. 



LTNDERTAKINGS operating under the provisions 

 of the Gas Regulation Act 1920, are required 

 to deliver gas of a declared calorific value to consumers, 

 and charges to individual consumers are to be based 

 upon the value of the total thermal energy supplied 

 to each. By calorific value is to be understood the 

 number of B.Th.U. produced by the com- 

 bustion of 1 cubic foot of gas measured at 

 60° F. under a pressure of 30 inches of 

 mercury and saturated with water vapour. 

 Under the Act, penalties are to be inflicted 

 upon the gas undertaking, if on any day 

 for a period of two hours or more the 

 calorific value of the gas supplied is more 

 than 6 per cent, below the declared calorific 

 value, nr if in any quarter the average 

 calorific value is less than the declared 

 calorific value. Embodied in Orders under 

 the Act are clauses governing the price per 

 therm (100,000 B.Th.U.) to be charged 

 by individual gas undertakings, and the 

 amount of dividend to be paid to pro- 

 prietors, as regulated by this price. Such, 

 in brief, are the main thermal clauses of 

 the Gas Regulation Act 1920 — the Charter 

 of Liberty of the gas industry in this 

 country, and the consumers' guarantee 

 that gas undertakings must and will " de- 

 liver the goods." 



Accurate gas calorimetry has long been 

 of importance for scientific purposes ; ex- 

 tremely accurate gas calorimetry is now of 

 consequence industrially and socially. The 

 accuracy of determination desirable will be 

 realised when it is understood that, in 

 terms of money, an error of 1 per cent, in 

 respect of the thermal value of the annual 

 gas supply of England, Scotland, and 

 Wales represents about 500,000/. 



Prof. C. V. Boys, at the annual meeting 

 of the Institution of Gas Engineers on 

 June 22, exhibited and described a record- 

 ing and integrating calorimeter (Fig. 1) 

 which he has designed and constructed 

 primarily to meet the requirements of the 

 Act in the matter of continuously recording 

 the calorific value of towns' gas. The in- 

 strument is, however, immediately appli- 

 cable to the determination and recording 

 of the calorific value and percentage varia- 

 tion with time of the calorific value 

 of any gas. It is of the water-flow 

 type, the same water being circulated continuously 

 through the apparatus and cooled to atmospheric 

 temperature, by the hot-air engine and cooling coil 

 seen at the bottom left-hand side of the figure. This 

 is an important consideration in continuous calori- 

 metry, as with another form of recording gas calori- 

 meter at present available the cost of water amounts 

 to about 20/. per annum. The fundamental features 

 of the instrument are : water and gas are doled out 

 positively at the correct respective rates, and the 



NO. 2755, VOL. I io] 



correction for gas volume as affected by temperature, 

 pressure, and humidity are likewise effected by a 

 positive operation. 



Water Measurement and General. — Water flows from 

 a tank, seen in the top right-hand corner of Fig. r, 

 where the level is maintained constant, through a 



nozzle into a celluloid bucket pivotted eccentrically 

 and so proportioned that it overbalances and empties 

 into the celluloid water-box shown in Fig. 1. After 

 emptying and draining, the bucket is released by a 

 clock every half-minute, and the operation is repeated. 

 The quantity of water delivered to the bucket can be 

 adjusted by a stop, so that if the gas is of the declared 

 calorific value, the rise of temperature of the water 

 flowing in the calorimeter is exactly io° C. On the 

 record sheet, therefore, corresponding percentage 



