
VALUE OF LIGNITES AND IRONSTONES. 175 
able quantity of mineral charcoal. Not very tough under the pick, and on 
weathering, breaking up along the planes. This form, is probably also 
in almost all cases composed of wood; but the material has undergone 
more thorough decay before the deposit of the next highest beds. 
Third.—Soft and friable; often with much mineral charcoal, but 
frequently brownish, and containing harder masses in some places. This 
variety, no doubt, often results from the thorough decomposition by the 
weather, of either of the others; and beds with this appearance would 
probably change their character for the better, more or less completely, 
if penetrated beyond the outcrop. There appear, however, to be some 
beds of this nature throughout; and these have been formed from peaty 
accumulations, with little wood. This class it is, which is most apt to 
contain much ash, and the beds under it, sometimes do not show clear 
lines of junction with the enclosing clays, but graduate into them. 
416. In the assays above given, it has not been thought necessary to 
restrict the examination to those beds which are of workable thickness, 
as a general comparison of the various seams, thick or thin, is of more 
value in giving an idea of the average quality of the lignites of the 
formation now known, and those which future exploration may bring to 
light, in the same region. The analyses, therefore, include a selection 
from the various sections; and several beds of good quality and thick- 
ness, with many of an inferior character, are unrepresented. 
417. Though giving the actual amount of hygroscopic and com- 
bined water, as found by analysis, it must be premised that it depends 
entirely on the conditions to which the lignites have previously been 
subjected; and that, by prolonged exposure to dry air,it might have been 
inmany cases very considerably reduced. It has, therefore, been 
thought advisable, in another place to reduce the results of all analyses to 
correspond to a certain percentage of moisture, that they may be better 
compared with each other, and with foreign lignites. The water content 
has been taken in the table, at 12 per cent., which has been adopted as 
the probable practical limit of dessication by dry air, under ordinary 
circumstances, of most of the samples. The lignites, it will be observed, 
are on the whole uniform in composition, and contain an average of 
over 40 per cent. of fixed carbon when the water is estimated at 12 
per cent. They thus fall somewhat behind the lignites found in the 
vicinity of the Union Pacific Railway; but it must be remembered that 
these only represent those seams which have been selected as workable 
from their good quality, and thickness; and also that many of them 

