Review of Prof. Johnson’s Report on American Coals. 327 
carbon was 1:2736 grain against hydrogen 0:07222 grain. As the sum 
of the hydrogen and oxygen is 5:972 per cent., and that of sulphur 
2°282, it is inferred that, in the volatile matter produced by the distilla- 
tion of this coal, there will be found 29-274—5-972—23-302 per cent. 
of its carbon. If the heating power be calculated from the above 
analysis by the organic method, without taking account of the sulphur, 
and only deducting of the hydrogen so much as is equivalent to the 
oxygen present, we have the calorific power expressed by 14°596 ;* 
or in pounds of water from 212°, for 1 of coal, 14:171. This is far 
above the actual result of experiment. The highest evaporative power, 
even when allowance was made for the heat expended on the products 
of combustion, as well as for that employed on the steam of the boiler, 
was but 10°1915. This will be evident from an inspection of the table 
of analyses of gases from the chimney.”—pp. 420-422. 
Interspersed throughout this portion of the Report are many 
other tables and observations of scarcely less importance, but 
which it is not in our power to introduce. At page 213 will be 
found a “ Tabular view of the proximate composition of Welsh 
furnace coals,” with a general description of the exterior and other 
characters of these coals. This table is highly interesting from 
the facility it gives us of comparing these with American coals of 
similar constitution. 
At page 584 is a table showing the “relative heating power of 
different bituminous coals as tested in making chain cable, com- 
pared with their evaporative powers.” This embodies the results 
of a series of experiments made in the smith’s shops of the navy 
yard simultaneously with those performed to prove the evapora- 
tive powers of the several kinds of fuel. This is followed by 
* Thus the carbon is 0:87634 of the coal, (considering all that was collected in 
the potash tube as carbonic acid ;) and this multiplied by 12,906, (Dulong’s result 
for the heating power of carbon,) we have left 11,284 for the computed heating 
power of the carbon inthe coal. This divided by 1-030 gives the steam generating 
power to 1 of coal=10,955. Deducting one eighth of 0-600 (the oxygen) from 
5°372, we get 5-297; and multiplying by 62,535, (the heating power of hydrogen,) 
we obtain 3-312, and the sum of these is 14,596, as above. By deducting the 
moisture (0:6696 per cent.) and the zwaste left in the third trial of this coal, (10-397 
per cent.) we have the remainder 88-933 per cent. of combustible matter, by which 
the total evaporative effect 10-1915 must have been produced. Hence 10-1915+ 
0-88933—=11:469=the evaporative power of the unit of matter actually burned in 
that experiment. Again: as in the sample analyzed, the combustible part is 
0-87634--0-05372-++-0:00600—0-93696, the carbon is 0-87634+-0:93606=0-9362 of 
that combustible; and 0-9362X 1290612083, the heating power of the carbon in 1 
of this combustible ; and, finally, 12083+1030=11-731=its evaporative power.” 
