IRON MANUFACTURE. 511 
Hecla iron No. 3—Chemists, Chauvenet & Blair. 
Washington Furnace—Chemist, Loomis. 
Hecla No. 3—Chemist, Prof. Dudley. 
Vesuvius No. 1—Chemist, Gill. 
Pine Grove Furnace—-Chemist, W. D. Wood. 
No. 1 iron, Hamden Furnace (analyzed for the Survey). 
eC 9 SS 
Some of the analyses were furnished by furnace companies, and are 
by well known chemists, whose names are appended to the analyses and 
are a guarantee of their accuracy. 
One of the most valuable qualities of this car-wheel iron is its 
property of chilling, or becoming white and hard when suddenly 
cooled, as when cast against a cold metal surface. Where such iron is 
made, it is generally cast in a chill bed or series of gutter-shaped 
moulds of cast-iron; this develops the white, hard layer in the pigs. 
The iron is then graded by number according to depth of chill and 
character of grain, as shown on the fresh fracture. This chill may 
run from being barely perceptible in No. 1 to two-thirds the depth 
of the casting in Nos. 4 or 5. 
Iron is graded thus at each furnace as it is made; there is, however, 
little correspondence between the analyses of the metal and the differ- 
ence of grade, as the following analyses willshow. They represent irons 
of different number made at the same furnace, and with the same mix- 
ture of ores, etc. ; only the amounts of silica and carbon are given, the 
amount of phosphorus not being subject to variation, unless the ore 
changes, as all present finds its way into the iron. 
1 Py, 3 
CORTE OVO Annee tot Caden BA Gc AcE CnC GaSe AEA AE am nT eae Mua nanan 3.24 3.43 ° 3.15 
SUT CO Maes eee eR et eae dome somasae di demeubeatee 1 SRNR Aeste det cetles os 2.33 2.33 3.85 
Lorp, Chemist. 
1. Gray No. 1 iron from Hamden furnace. 
2. No. 2 iron from Hamden furnace. 
3. Silver Gray iron from Hamden furnace. 
All are made from gray limestone ore with charcoal. No. 3 shows 
the cause of its silvery character in the high silica percentage. The slags 
produced in these furnaces are acid silicates; they are illustrated by the 
following analyses, made in the laboratory of the Survey: 
