Natural ventilation is impracticable in flat deposits worked by drifts and without shafts.
He had already prepared for a further advance by making an expedition into the heart of Mississippi as far as Meridian, destroying railways and making impracticable, for a season, the transfer of military operations to that region; and on Grant becoming general-in-chief (March 1864) he was made commander of the military division of the Mississippi, including his Army of the Tennessee, now under McPherson, the Army of the Cumberland, under Thomas, and the Army of the Ohio, under Schofield.
Since the condition of heat-isolation is impracticable, the condition of maximum entropy cannot, as a rule, be directly applied, and it is necessary to find a more convenient method of expression.
Passed into first line for the further advance on Cantaing, which proved to be impracticable before nightfall.
The chief trouble was that acetone expands a small percentage of its own volume while it is absorbing acetylene; therefore it is impossible to fill a cylinder with acetone and then force in acetylene, and still more impracticable only partly to fill the cylinder with acetone, as in that case the space above the liquid would be filled with acetylene under high pressure, and would have all the disadvantages of a cylinder containing compressed acetylene only.