METALS. 



425 



The cast-iron wheels weighed 550 Ibs. each. 

 These tests are rather crude in character, but 

 they establish the fact, pretty well known be- 

 fore, of the superiority of cast steel over cast 

 iron, in resisting the effect of hard blows. 



The Protection of Iron Ships. The latest 

 invention for the protection of iron ships from 

 oxidation is that of Messrs. Demanel & Bertin, 

 who distribute about the inner side of the 

 shell tubular reservoirs made of zinc, which 

 are riveted to the plates, and place the metal 

 in perfect communication with the iron hull. 

 These reservoirs are charged with sea-water, 

 which is changed every day. Bands of zinc 

 carried in all directions connect the various 

 reservoirs, and strips are here and there 

 brought to the outer side and made to com- 

 municate with the sea. An electrical action, 

 it is asserted, is thus produced, which protects 

 the iron from oxidation. The authors say that 

 experimental boats kept in very salt water for 

 a year, with these appliances attached to them, 

 do not "exhibit a trace of oxidation in any 

 part. 



Chromium and Titanium in Pig-iron. 

 Messrs. A. N. and S. D. Hayes, of Massachu- 

 setts, contributed a paper to the Scientific, 

 American, reporting the results of frequent 

 chemical investigations made by them upon 

 the altered character of some pig-irons, re- 

 sulting from the presence of the oxides of 

 chromium and titanium. They say : 



Both, the oxide of chromium and oxide of titanium 

 seem to act in the furnace or the crucible in a way to 

 withdraw a portion of the carbon, or prevent that 

 true union of carbon with a portion of the iron, which 

 constitutes gray pig-iron^ without the metals of these 

 oxides really alloying with the iron, and thus indi- 

 cating the cause of change. We have analyzed sam- 

 ples of pig-iron where the alloys of chromium or 

 titanium existed in the pigs, and where the oxides 

 accompanied the ores in the beds, but we were not 

 prepared to find an influence exerted on the quality 

 of the pig-metal without the refractory metals form- 

 ing a part of the composition. 



The occurrence of oxide of manganese with iron 

 ore is common, and titanium compounds are often 

 found in both magnetic and brown iron ores, as in- 

 soluble substances, in small proportions, and these 

 compounds combine with and are removed by the 

 fluxes without injury to the pig-metal. These com- 

 pounds of titanium are the cause of the often superb 

 blue color of the cinder, produced under varying con- 

 ditions of glassy or stony character, and must be care- 

 fully distinguished from those we regard as more 

 detrimental in their influence on the metal. 



In a number of analyses of iron-ores we had found 

 both oxide of chromium and oxide of titanium in a 

 state rendering them soluble in diluted acids, and 

 in a condition to escape . detection in the ordinary 

 modes of analysis. Both magnetic and brown iron 

 ores have been found to contain either oxide of 

 chromium or oxide of titanium hi this soluble state. 

 Among the samples from contiguous beds, this di- 

 versity in composition made by^the presence of some 

 oxide of chromium or oxide of titanium existed ; and, 

 while the bulk of a bed of ore was pure, continuations 

 of the bed or associated ore yielded -notable weights 

 of oxide of chromium or oxide of titanium in the dif- 

 ferent samples. 



The suggestion we would make to the iron-master, 

 in view of these facts, is the possibility of the quality 

 of the pig-metals in anomalous cases being greatly 



influenced by the admixture of some ore containing 

 the oxides of chromium or titanium with the basis 

 ore of good quality. This may take place by the 

 main bed being crossed by veins of mixed ore, or by 

 the workings passing into contiguous beds where one 

 kind of ore is used. In other cases, where the iron- 

 master can gain a great advantage arising from mix- 

 ing ores, one of the kinds may contain the contami- 

 nating oxides and injure the iron. 



We subjoin some results of analysis, showing the 

 proportion of oxide of chromium to the metallic iron 

 contained in the ores : 



1. Magnetic ore iron, 49 ; oxide of chromium, 1.40. 

 2. Hematite ore iron, 42.47; oxide of chromium, 

 1.60. 3. Brown massive ore iron, 54.32 ; oxide of 

 chromium, 1.90. 4. Same iron, 46.70 ; oxide of 

 chromium, 1.04. 



More traces have been discovered in some cases, 

 while in other instances a larger proportion of chro- 

 mium formed an alloy with the iron produced from 

 the ore. 



Malleable Cast Iron. An account of the 

 manufacture of this article, as now carried on 

 in the most celebrated German founderies, is 

 supplied by La Genie Industrielle. We quote : 

 " The makers keep secret the brand of iron 

 which they employ, but it is well understood 

 that the brands are not the same in different 

 establishments. The iron is melted in plum- 

 bago crucibles, holding about 30 kilog. They 

 are covered with porcelain lids, to keep put 

 impurities and cinders, which reduce the high 

 heat requisite for the process. The fire in 

 which the crucibles are placed is from 630 m. 

 to 940 m. square, and is surrounded with 

 bricks of porcelain earth. The use of blast is 

 not advantageous, since the economy of time 

 is offset by a greater consumption of coke. 

 The natural draught of the chimney is suffi- 

 cient when the furnace is properly constructed. 

 An essential condition of success is a high heat 

 at the moment of pouring. Practice enables 

 the caster to estimate the heat of the furnace, 

 and he recognizes the precise moment by 

 plunging a bar of red-hot iron into the cruci- 

 ble, from which, upon being withdrawn, the 

 metal flies off in sparks. The crucibles are 

 raised with tongs with curved jaws, and the 

 pouring is done with all possible speed the 

 surface being first cleaned. By cementation 

 the casting acquires the properties of wrought 

 iron, having some analogy to steel. The oper- 

 ation consists in subjecting the castings to a 

 prolonged red-heat in a bath of pulverized red 

 hematite. They are arranged in boxes of cast 

 iron called muffles. These are square, and 

 with air-tight covers. In arranging the cast- 

 ings in the boxes, they are placed in layers 

 alternately with layers of hematite. The ce- 

 menting furnace is very simple. The grate is 

 in front, and the draught of the chimney car- 

 ries the hot air around the boxes. _The heat 

 should be conducted with care, starting rather 

 vigorously, in order to reach the desired tem- 

 perature quickly ; then, supplying the furnace 

 at regular intervals. The cementation lasts 

 three, four, and five days, according to the size 

 of the pieces. A charge is about 350 to 450 

 kilog. of castings. In arranging the charges, 



