[stansfield-gilmore] carbonization OF LIGNITES 91 



regular series, which was stored in a desiccator, for the first 4j hours 

 in a closed weighing bottle and afterwards in a specimen tube closed 

 with a rubber stopper, showed gains in weight of 0-05% in 1| minutes, 

 0-2% in 41 hours, 0-4% in 3 days, 1-6% in 16 days, and 2-2% in 

 26 days. The losses in calorific value were 2 • 6% in 16 days and 3 • 8% 

 in 26 days. The losses in calorific value are apparently slightly 

 greater than can be accounted for by occlusion of air or unavoidable 

 absorption of moisture. Study of this phenomenon is reserved for 

 later investigation, as the results obtained are insufficient for reliable 

 interpretation. 



Slow Carbonization Series: — Six completed tests were run in this 

 series over a temperature range of from 390°C, to 700°C. The 

 procedure was the same as in the regular series, except that, instead 

 of the retort being heated rapidly up to the desired temperature, it 

 was first heated to about 250°C in the oil bath, then transferred to the 

 lead bath, and its temperature slowly raised to the required point. 



The results show a strong similarity to those of the regular 

 series, but for any given final temperature, slow heating caused a 

 slightly lower loss of volatile matter. The calorific values were 

 rather erratic but showed no marked difference from the above. It 

 should be noted in this and the following cases, that even where the 

 yields and the calorific values are similar in two series, it is no 

 indication that the by-products are also alike. As has already been 

 stated, the by-products are to be examined in a later investigation. 



This series was not repeated after the standardization of the 

 time factor. The calorific values obtained were therefore omitted 

 from the curves and tables. 



Vacuum Series: — Eight completed tests were run in this series 

 over a temperature range of from 355°C. to 705°C. The procedure 

 differed from the regular in that the inlet tube of the retort was closed, 

 and the outlet tube connected through a receiver to a good water 

 pump; the pressure in the retort being thus kept below 25 mm. of 

 mercury. 



The results show, as was expected, that at any temperature the 

 percentage of volatile matter driven off is greater than at ordinary 

 pressures; but the difference is not so great as was expected. The 

 calorific value of the residue is the same as in the regular series at 

 350°C., above this temperature it is distinctly less. 



Steam Series: — Six completed tests were run in this series over a 

 temperature range of from 355°C. to 665°C. The general procedure 

 was followed, except that a gentle current of steam was passed in 

 through the inlet tube whilst the retort was being heated, dry coal gas 

 being passed through as usual during the cooling period. 



