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numbers, for as a rule the more silicon in iron the greater its value in any special brand. Even if the trade should not, in time to come, require a numbering of grades on account of the practicability of ordering by specified analysis in purchasing foundry, bessemer, gray forge, mill, or basic pig irons, it will be essential to have some means of brevity as by numbers in denoting grades in the market reports of prices: And the method presented by the author in Table 22 seems to him as simple and practical as could be offered or enforced by practice for such ends.
TABLE  22.
Silicon.     ...........	No. i Iron. 2.75 to 3.00	No. 2. 2.50 to 2.75	No. 3. 2.25 tO 2. SO	No. 4. 2. no to 2.2S
Sulphur ......................	.01 to   .04	.01 to   .04	.01 to   .04	.01 to   .04
Silicon.             ...........	No. 5.	No. 6.	No. 7. 1.25 to 1.50	No. 8. I.OO tO I.2S
Sulphur ...................	.02 to   .05	.02 tO    .05	.03 to   .06	.03 to   .06
Silicon.	No. 9. .75 to i.oo	No. 10. .So to   .75		
Sulphur .................	.04 to   .07	.04 to   .10		
Numbering the grades from i to 10, advancing in silicon .25 and sulphur .01 to .04 or more in each grade, as shown in Table 22, gives a range that may be said to include all the necessary irons that are now used in making castings, or for the manufacture of steel or wrought iron, except the so-called softeners or ferro-silicon irons. When purchasing ferro-silicons or softeners one should also know, aside from the silicon, the amount of sulphur, phosphorus, manganese, and total carbon they contain, as these elements can vary greatly in the same brand, or similar percentages of high silicon iron, vary much more than in irons having lesse highest point of any oneled as well as unchilled castings. analysis which may be given is simply an average of the whole, generally taken from the two ends andith the uncertainty of furnace workings when in urgent need of ten hundred             jon of iron; and Sir........................    2,720     "