STATE GEOLOGIST. 125 
means of a stop cock and funnel. The oil dripped into the open furnace 
making a sight feed arrangement. The blast was furnished by a positive 
rotary blower through a 34 inch pipe. 
The mode of operating the furnace was as follows: At the bottom 
of the cylinder beneath the furnace proper there was placed a small shallow 
iron pan into which the oil dripped from the feed pipe and which served 
as an evaporator for the oil. When ready for operation a small bunch 
ol waste saturated with oil was placed upon the pan, ignited and covered 
with a few pieces of wood and charcoal. Upon this small charge of fuel 
there were now placed pieces of fire brick, the size of a large walnut, 
which filled up the cylinder completely and served the purpose of offering 
resistance to the passage of gases and air, thus mixing them for proper 
combustion. The air was blown in through three small tuyeres distrib- 
uted around the cylinder. As soon as the charcoal was fully ignited, the 
kerosene was allowed to flow slowly and a weak blast maintained. Grad- 
ually the flow of oil and the blast were increased, until the maximum sup- 
ply was reached. 
Before the supply of oil had begun, a fire clay tile was placed across 
the furnace occupying the space formerly taken up by the muffle. Upon 
this tile were placed the crucibles or biscuit saucers carrying the samplcs 
to be ignited. At the same time a porcelain tube containing the platinum 
wire and thermo-couple of a Chatelier pyrometer was placed in position, 
just touching the mixtures to be heated. 
The rise in temperature was readily followed by means of the pyrom- 
eter whose millivolt meter is set up in a closet at a distance of about 7 
feet from the furnace. 
The question now arose in regard to the temperature to be employed 
in the burning. It was at once evident that the work to be accomplished 
by the heat is two-fold. | 
First; the carbonic acid must be expelled from the calcium carbonate. 
Second, the silicate must be decomposed and the finely divided silica 
converted into lime silicate, soluble in acid. 
The first function obviously fixes the lowest limit of the temperature 
to be employed. From the work done by Prof. Hertzfeld, we know 
that at a temperature of 1050° C. the carbonic acid is completely expelled. 
Lunge and Schochor employed a temperature between 1060° and 1120° 
Centigrade, their statements being in this respect not as definite as could 
be desired. However, from the extensive knowledge in existence in regard 
to the unlocking of silicates by the J. Lawrence Smith process, we know 
that it is not necessary to carry the temperature very high and this is 
also not desirable owing to other considerations. The heating must not 
be carried so high that silicates and aluminates analogous to those of 
hydraulic cements are formed, reactions which are entirely uncalled for 
in this process, and which might result in the crystallization of compounds. 
