﻿64 cox. 



A qualitative experiment will show in a few minutes whether or not 

 a coal suffers mechanical loss by the official method. It has been demon- 

 strated that the latter is thoroughly applicable in the analysis of some 

 of the Philippine coals — that is, to bituminous coals which sinter together 

 and to non-coking coals where there is no mechanical loss — while it is not 

 at all tenable and is just as thoroughly inapplicable in the analysis of 

 certain other native coals. Therefore, the problem of establishing an 

 entirely satisfactory method is not nearly so simple as it was at first 

 thought to be. Any method where a correction is involved is not satis- 

 factory, but it would necessarily have to be used if an attempt were made 

 to formulate a method applicable alike to all the coals of the Archipelago. 



For the present, in order to facilitate direct comparison with coals 

 from other sources we shall continue to use the official method in this 

 laboratory wherever it is applicable, but in those cases where it entails 

 large losses we shall employ the smoking-off process, followed by seven 

 minutes over the full flame. The experiments show that less than seven 

 minutes would siiffice, but since no loss is entailed by the seven-minute 

 treatment it is well to maintain uniformity. The means of estimating 

 moisture, fixed carbon and ash as outlined by the committee are satis- 

 factory in these non-coking coals, provided the volatile matter is carefully 

 smoked off from that portion on which the ash is determined. The 

 recommendations for the determination of ash are to "burn the portion 

 of powdered coal used for the determination of moisture, till free from 

 carbon. If property treated, this sample can be burned much more 

 quickly than the dense carbon left from the determination of volatile 

 matter." In the case of non-coking coals there seems to be no difference 

 in the time required, whether the sample used for the determination of 

 moisture or that left from the determination of volatile matter is em- 

 ployed. In fact there is this to be said in favor of the latter that it 

 is all ready to burn; if the former is used it must first be carefully 

 smoked off with the crucible lid on tight to prevent mechanical loss 

 of ash. 



If the smoking-off method is used only when the official method shows 

 mechanical loss, it will suffice for commercial w^rk to neglect the 

 difference in the breaking down of the hydrocarbons of the coals by dif- 

 ferent heat treatment, as is indicated by the data from Negros coals 

 Nos. 21 and 23, and to consider the results obtained by the smoking-off 

 process directly comparable with the analyses of coking coals analyzed 

 according to the directions of the Committee on- Coal Analysis. If coals, 

 the volatile matter of which is high in heavy hydrocarbon compounds, 

 are analyzed by the smoking-off method then the factor of the difference 

 in the breaking down of these compounds is of sufficient magnitude to 

 demand consideration. 



