2 
& 
TRANSACTIONS OF THE SECTIONS. 55 
Taking a piece of highly sensitive photographic paper, which would blacken ina - 
few seconds by the light of an Argand gas-burner, he threw upon it a condensed 
spectrum which had been previously analysed by a peculiar yellow medium, and then 
__ by means of a mirror reflected the strong light of the sun upon the paper. It was, ° 
therefore, under the influence of the reflected radiations without any change, and 
also of the spectrum from which the chemical agency had been as nearly as possible 
separated. The result was, that the paper was blackened over every part, except 
that portion upon which the strong line of spectral light fell, which was protected 
from change and preserved as a white band in the midst of the darkened paper. This 
experiment was thought by the author strongly confirmatory of the view which he 
had taken, that actinism, or the chemical principle, and light, so far from being 
identical, were opposed in action to each other. 
Analysis of Wrought Iron produced by Cementation from Cast Iron. 
By Prof. W. A. Mitirr, M_D., F.RS. 
The following are the results of an examination of the chemical composition of a 
specimen of brittle cast iron, which was by a subsequent process converted into 
malleable iron by cementation. 
The ore from which this iron was obtained is the Lancashire brown hematite 
from the neighbourhood of Ulverstone; it is smelted with charcoal instead of with 
coke: the articles to be rendered malleable are first of all cast in the desired form. 
They are in this state formed of a nearly white, very hard, brittle iron, which exhi- 
bits a crystalline grain on fracture. ‘To convert these extremely brittle articles into 
malleable iron fit for the forge, they areimbedded in powdered hematite and maintained 
at a red heat for some hours; the carbon is thus gradually removed by inverting the 
usual operation of converting bar-iron into steel, and the result is the production of 
a tough iron, which may be hammered either hot or cold. 
A careful qualitative analysis showed that besides iron, carbon and silicon, traces 
of aluminum, sulphur and phosphorus were present, while no arsenic, antimony or 
manganese were there; titanium was not detected. 
The author stated in detail his process for the analysis, and added the following 
observations :— 
It is to be noticed that considerable change in the specifie gravity occurred in the 
iron after cementation; it was forged, and was then found to have increased in den- 
sity: the brittle iron had a specific gravity of 7°684; the malleable, 7°718. 
The results of analysis are briefly these ; the quantity both of carbon and silicon 
are materially diminished by the cementation, though still the proportion of both is 
greater than in good bar-iron. It also appears that the portion of carbon which is 
- insoluble in acids is nearly the same both before and after the iron has been rendered 
malleable, the diminution being confined almost to that portion of carbon which 
was chemically combined with the metal, and which therefore would be in a state 
for propagation through the mass more readily by cementation. 
Cast Iron. 
Brittle. Malleable. 
Specific gravity .,....000... 7°634 7°718 
TOPS i iinen ta viphnadatsses <oase 
CAUGON: ccanasecdnags nas cas -4: 2°80 0'88 
BACON, feassxeye=chasvsexsenes OCOD E 0°409 
Aluminum .oecccccsresseeeee trace trace 
Manganese ..sssesegseereeeee NONE none 
Pitaris(l:.'sevaseecnkecgecaccs 0 0 
ALSEDIC seeceecsseseteceeeees NONE none 
Sulphur ...cceccssereeseeeree O'O15 
Phosphorus,....sse+ssseeee08 trace trace 
SARs: swedacd cece basesesvas <3 0°DOB 
Carbon combined ......... 2°217 0°434 
Ditto uncombined .......5. 0°583 0°446 
