CORRESPONDENCE.

Taranaki Daily News, Volume LVII, Issue 273, 28 April 1915, Page 3

CORRESPONDENCE.

mg. | BASIC SLAG. 1 To the Editor. , Sir,—The. importance of this subject i to the farmers of Taranaki should be a ' sufficient excuse for further correspondence, with a view to eliciting some authoritative statement as to the real facts' of the case. The matter is of greater importance than may appear to the casual reader, as Taranaki .soil, in .common with the soils of most parts of the West Coast of this Island, is deficient in phosphoric contents, and jjhosplmtic rocks have not hitherto been found, if we except the rare instances of small nodules in the limestones. These instances have been so rare as to be considered exceptional. Mr. Smith's letter in your issue of the 10th inst., unfortunately, does not help us much, as Mr. j MeLaurin's analysis only bears out my 1 contention that Taranaki ironsand is re- j markably free from phosphorus. Basie | slag ? as a fertiliser, is sold entirely «n its pliosphatic content, which varies from j twelve to twenty-live per cent., accord-' ing to the amount of the impurity pre- '■■ sent in the iron' from which steel is being made. The basie slag imported to New Zealand usually contains from sixteen to twenty per cent, of phosphate. According to the analysis given, the percentage of phosphorus in Taranaki ironsand is infinitesimal, and none of the Jinxes examined by the analyst contain more than a fraction of one per cent, of phosphorus. Commenting on the analysis, Mr. MeLaurin remarks that "this ironsand contains only small percentages cf phosphorus and sulphur, and should tlkerefore prove suitable for the acid Bessemer process." Now the acid Bessemer process is not suitable for making steel <aut of iron that contains any more than a very small quantity of phosphorus, hence Thomas and Gilchrist's •process, which consists of lining the vessel for containing the molten iron with lime, which picks up the phosphorus and retains it, instead of allowing' it to be re-absorbed by the iron, as it would be if the vessel or chamber had a silica, lining. It was not till some years after • Thomas and Gilchrist's discovery of this method of removing the impurities from the iron that the value of the resulting slag as a fertiliser wag discovered. It is true that slag is now produced by other than the Bessemer process of making steel, but the principle is the same,' Homely, the use of iron rich in phosphorus and the use of lime as a base. 1 may be wrong in my deductions, but as I read the Government Analyst's report, slag Diade from Taranaki ironsand would not, as a fertiliser, be worth cartinj i away.—l am, etc., FARMER. Mokau, April 25, 1915. \