1918.] 
The N.Z. Journal of Science and Technolooy. 
95 
in mind that inferior grades can be used within limits at the expense of 
greater energy-consumption and loss of carbide. 
The analysis of a typical sample of commercial carbide is shown in 
Table 2 to consist of 86 per cent, carbide, 1 per cent, carbon, 10 per cent, 
lime, 0*6 per cent, silicon carbide, 1 per cent, ferro-silicon, 0-4 per cent, 
sulphur compounds, and 1 per cent, magnesia compounds ; and in calcu¬ 
lating the quantity of raw material required, say per ton of carbide, it is 
necessary to take account of the amount of carbon and lime which passes 
through into the product. 
Referring to Table 3, this shows the quantity of material required 
per ton of carbide packed in drums or otherwise, also the energy re¬ 
quired per ton and the output per horse-power year. The calculations 
of the quantity of material required are based upon the quality of the 
raw material and finished material given in Table 2. The quantities 
are given in terms of the quantity of carbide packed for sale, after 
taking into account all losses, in addition to the more usual method 
of stating the energy-consumption in terms of the furnace output. 
The net energy utilized in the furnace is also stated, and a furnace 
efficiency of 50 per cent, is adopted as being attainable without undue 
effort, and with the use of high-quality raw material as specified in 
Table 2. 
The usual assumption in regard to the production of carbide is 1^ tons' 
per horse-power year. It should be borne in mind that this is the produc¬ 
tion in terms of the horse-power of the furnace, and takes no account of 
the energy used in auxiliary apparatus or of the carbide lost in crushing 
and packing. 
Table 3 shows an output somewhat less than the usual assumption, and 
the author ’believes it to be nearer the average than the figure quoted. The 
yield given in Table 3 is 1-27 tons produced by the furnace per horse¬ 
power year of 8,000 hours, delivered to the furnace, which is equivalent 
to 1’143 tons per horse-power year delivered to the works, after taking 
into account the energy used by auxiliary apparatus, and T09 tons 
per horse-power year delivered to the works after allowing for losses in 
crushing and packing. 
As regards the quantity of coke and limestone' required, this depends on 
the quality of the raw material and also of the product. Carbide of the 
quality shown in Table 2 contains 1 per cent, of carbon and some further 
carbon in combination with silicon ; consequently an addition of about 
2 per cent, has to be made to the charge to compensate for this loss. The 
coke is assumed to be of the quality set out in Table 2—viz., 88-4 per cent, 
dry coke — and on this basis it is shown in Table 2 that 0-587 ton of coke 
is required per ton of packed carbide, and allowing for losses in handling 
the coke, say, 0*6 ton. Likewise with the lime it is shown in Table 2 that 
the typical sample of carbide contains 10 per cent, of lime in its composition. 
This requires an addition of 12J per cent, to the charge in order to com¬ 
pensate for the loss, so that if 96J per cent, lime is used a charge of 
0-95 ton, corresponding to 1-.62 tons of 98 per cent, limestone, must be 
allowed for the charge per ton of packed carbide (Table 3). As regards 
both coke and limestone or lime, a further allowance in weight must be 
made for moisture, which has to be borne in mind in purchasing these 
commodities. 
The net thermal energy required per ton of 86 per cent, carbide produced 
is calculated by Bingham at 2,350 kilowatt-hours. The gross energy on 
