96 The N.Z. Journal of Science and Technology. [Mar. 
the basis of a 50-per-cent, furnace efficiency is 4,700 kilowatt-hours, and 
allowing 10 per cent, loss in conductors and auxiliary apparatus the 
total energy delivered to the works amounts to 5,222 kilowatt-hours per 
ton of 86 per cent, carbide produced. Allowing again for losses in crushing 
and packing, we arrive at a gross figure of 5,480 kilowatt-hours per ton of 
carbide packed for sale. 
The electrode-consumption is based upon the use of carbon electrode, 
which is considerably higher than graphits electrode; but the latter is 
more expensive, and in all probability less economical under New Zealand 
conditions. The rate of consumption as shown in Table 3—viz., 66 lb. 
per ton of carbide produced, or 69-3 lb. per ton of carbide sold — is 
high, but it would not be safe to reckon on a smaller figure under average 
conditions. 
Preliminary estimates were made of the cost of producing 500 tons 
per annum and also 750 tons per annum, but the results w.re not sufficiently 
promising to warrant further investigation. Preliminary estimates, how¬ 
ever, indicated that an output of 1,000 tons per annum might be profitable, 
depending upon local circumstances, and accordingly detailed estimates 
have been prepared of the cost of producing and marketing the quantity 
mentioned, and they are scheduled in Table 4 hereto. As this did not show 
a sufficient margin for contingencies, detailed estimates were prepared of the 
cost of producing and marketing 1,500 tons per annum, and they are 
scheduled in Table 5 hereto. Referring to the estimates for the 1,000 tons 
production, the capital investment — viz., £12,000—includes buildings, 
furnace, crushers, canning, and packing, but does not include provision for 
a coke-furnace or a lime-kiln, as it is assumed that the coke and lime are 
purchased on the open market. 
Materials .—As regards the materials, coke is assumed to c'ost £1 10s. 
per ton. This is higher than the normal price of gas-coke, but, as the 
quality required for carbide-making is better and the coke of metallurgical 
quality difficult to obtain, the price is not high. On the other hand, it is 
quite probable that the demand will create a supply of the proper quality 
at cheaper rates, so that there is a possibility of saving, say, 5s. per ton 
on this item, equivalent to 3s. per ton of carbide. 
Lime— Taking lime next, this is entered at £2 12s. 6d. per ton, 
which is the normal price in New Zealand. This is a high price, and, 
given a larger demand, it should be possible to reduce this to £1 10s. 
per ton or less if the carbide-factory be at the kiln, thereby effecting 
a saving of £1 2s. 6d. per ton of lime and £1 Is. 4d. per ton of packed 
carbide. 
Cost of Power .—As regards the cost of power, this is quoted at £4 per 
horse-power year. This value, whilst exceedingly low for general industrial 
purposes, is high for such purposes as calcium carbide, and would be almost 
prohibitive for carbide intended for the world market, and for that purpose 
it would be necessary to establish the works in some place where power 
could be developed for, say, £1 10s. per annum, and where harbour facilities 
exist in conjunction therewith and where the raw material is readily 
obtainable. But as it is premised that the carbide is manufactured for local 
consumption, and possibly in conjunction with some existing industry, the 
figure is one which brings the manufacture within the range of possibilities. 
This figure is about the bottom price now ruling for a supply from Lake 
Coleridge, and is a figure which cannot be much reduced whilst the supply 
is limited to the present scale of operations, nor is it probable that it could 
