MACHINE FOR MAKING BLUE MASS. 
bevelling is sufficient to produce a pushing and lifting ef- 
fect on the mass ; the knife never rises and falls in the same 
place, at any two consecutive movenienis, but is continually 
revolving about six revolutions of the crank, producing 
one in the knife. Every part of the contents of the 
cylinder is visited by its effects. The mass is not exposed 
to the action of the air in this machine to the same extent 
as it is in the triturating process, nor is there so great a sur- 
face for evaporation. It is believed that the colour of blue 
mass becomes darker by age, a change due possibly to 
an oxidizing action exerted on the surface of the minute 
globules. The colour appears to darken with the minute- 
ness of the globules, or state of division of the mercury also, 
because every succeeding operation of the machine caused 
the colour to deepen ; and the inventor says that by con- 
tinuing its action for a length of time, the colour may be made 
considerably darker than the mass as finished under our ob- 
servation. During the progress of the experiment as before 
stated, the committee took the precaution to set aside a 
sample of each quarter of the mass in each of the operations. 
In subsequently comparing these under a good lens, the 
gradual progress of the division of the mercury is very ap- 
parent, until in the finished article the globules are barely 
visible, and when compared with a mass of acknowledged 
good quality, made by the triturating process, the degree 
of division was equally great, if not greater, and fewer 
instances of separate larger globules, as are often found in 
mass. 
The fibrous texture of the conserve is reduced to a uni- 
form state by the cutting action of the knife which is very 
sensibly visible on comparing the earlier with the later 
samples of the mass. 
In reviewing the operation, we are of opinion that the 
power of one man is not sufficient to turn the machine with 
its full charge, with that rapidity requisite to make the pill 
mass in six hours. We believe that it is much better adapt- 
