Jenkinson. — Manufacture of Ivon and Sled in New Zealand. 513 



The resulting pig would at this price have a New Zealand market of 

 about 4,000 tons per annum for foundry use, but the small cost of the 

 plant — say, £25,000 — ^would enable even this small output to be manu- 

 factured as an economic proposition. Another 1,000 tons could be refined 

 while still molten to cast steel for steel castings, a good demand existing 

 for these at remunerative prices. This, however, is the greatest extent 

 to which the utilization of New Zealand iron-ores is likely to rise for many 

 years, and all talk of plate and rail mills, shipbuilding, &c., and of New 

 Zealand as a factor in the steel and iron business of the world, is quite 

 ridiculous at present. 



Art. LV. — Studies ov the Lime Requirements of certain Soils. 



By Leonard J. Wild, M.A., F.G.S., Lecturer in Chemistry, Canterbury 



Agricultural College. 



[Read before the Philosophical Institute of Canterbury, 1st December, 1915.] 



I. 



Under this heading Hutchinson and MacLennan, in the Cambridge Journal 

 of Agricultvral Science for March, 1915, describe a very rapid and simple 

 method for determining the lime requirement of soils. Since so much is 

 spoken and written, while so little is really known about the lime require- 

 ments of our New Zealand soils, it seemed desirable to test the validity of 

 this method, which claims to give valuable and accurate information for 

 very little trouble. The present article contains an account of such an 

 inquiry, together with the results obtained from trials with certain Canter- 

 bury soils. 



The method is based on the absorptive capacity of the soil for calcium 

 carbonate presented to it in solution as bicarbonate. A known quantity 

 of bicarbonate in solution is left in contact with a known weight of soil for 

 a few hours, at the end of which time the amount of lime in the solution is 

 again determined. The quantity of lime lost by the solution is the quantity 

 required to satisfy the given weight of soil, and fi'om these figures the per- 

 centage requirement of the soil, and hence the required weight of lime per 

 acre, is calculated. To obtain this last result, the apparent density of the 

 soil must also be determined. 



The calcium-bicarbonate solution is easih' prepared in an ordinary 

 " sparklet " or refiUable " soda-water " apparatus, for which bulbs of com- 

 pressed carbon dioxide are used. Into this an excess of finely divided 

 calcium carbonate (10 gr. to 12 gr. pure pptd. CaCOa) is put before the gas 

 is admitted. The solution of CaH.^(C03).. thus formed is siphoned off, and 

 about one-third of its volume of water is added, after which it is filtered 

 free from undissolved carbonate, standardized by titration with decinormal 

 sulphuric acid, using methyl orange as indicator, and is ready for use. 

 The strength of a solution prepared in this way is about one-fiftieth normal. 



Ten grams of the soil under investigation is placed in a bottle or flask 

 of about 500 c.c. capacity, and 200 c.c. to 400 c.c. of the solution is added. 

 The air in the bottle is displaced by a current of COg to prevent the pre- 

 cipitation of CaCO:^, and the bottle is placed in a shaking-machine for three 



17— Trang. 



