TRANSACTIONS OF SECTION G. 511 
chiefly by J. E. Stead, by the method of heat-tinting which differentiates 
between those portions of a polished steel surface rich in phosphorus and those 
free from it by the difference in the rate of oxidation. The banded distribution 
of the phosphorus thus reproduces itself as bands of different depths of tinting 
on the surface after exposure to heat. More recently the author and J. L. 
Haughton at the National Physical Laboratory have worked out a method of 
tracing the phosphorus distribution in steel by means of a new reagent. This 
is a solution of ferric chloride rendered acid by hydrochloric acid and containing 
in solution small quantities of the chlorides of copper and tin. When a steel 
surface is exposed to this reagent electro-chemical replacement occurs, a small 
quantity of iron passes into solution, and a corresponding amount of copper is 
deposited as a thin film on the surface of the steel. In an ideally pure steel 
this deposit would be uniform over the entire area of the ferrite constituent, 
but in a phosphoric steel the copper film is deposited first on those ferrite 
regions which are most nearly pure, those regions richest in phosphorus being 
left unaffected for a long time. Seen under the microscope, the surface thus 
‘etched’ by the selective deposition of copper presents a well-defined appear- 
ance which at one point reaches a development corresponding accurately to the 
pattern produced by the older method of heat-tinting; at an earlier stage, 
however, features are shown which escape detection by the older methods. A 
study of these features leads the author to trace back the origin of the banded 
structure of phosphoric steel to processes which are known to occur in the first 
solidification of a ‘solid solution’ alloy, so that the coarser or finer banding 
of the finished steel depends upon the scale of crystallisation which took place 
in the original ingot, in spite of the fact that the crystalline structure may have 
been entirely changed repeatedly as the result of thermal or mechanical treat- 
ment. This great persistence of the ‘geographical’ distribution of phosphorus 
is to be ascribed to the low velocity of diffusion of iron phosphide when present 
in solid solution in iron. The paper was illustrated by numerous photographs 
and diagrams. 
4. Notes on some Tests of Petrol Motor Fire-Engines, and the 
Frictional and other Resistances to the Flow of Water through 
Canvas Fire-Hose. By Professor T. Hupson Bears, M.Inst.C.H. 
The experiments described in this paper were carried out on two fire-engines. 
The first engine, supplied by Messrs. Merryweather, was driven by a four-cylinder 
‘Aster’ petrol engine, the cylinders being 53 inches diameter, with a 6}-inches 
stroke, and the speed 1,000 revolutions per minute. The pump was of the ‘ Hat- 
field’ reciprocating type, and had three single-acting plungers of 7-inches bore 
and 5-inches stroke; the barrels were arranged radially round a common crank-pin 
at an angle of 120° to one another. The pump was driven by a chain, 53 inches 
wide, and was geared down 4:47 to 1; with this gearing 1,000 revolutions of the 
motor would correspond to 224 revolutions of the pump. 
The second engine, supplied by the Halley’s Industrial Motor Company, was 
driven by a six-cylinder petrol engine, the cylinders being 5 inches in diameter 
with a 5!-inches stroke, stated to be capable of developing 60 h.p. at 1,000 revolu- 
tions per minute. The pump, made by Messrs. Mather & Platt, was of the 
centrifugal type, and was driven direct from the engine by enclosed gearing run- 
ning in oil; the pump was geared up about 3 to 2 that is to say, when the engine 
was making 1,000 revolutions the pump would be making about 1,500 revolutions 
per minute. The engine carried a reciprocating exhauster air-pump, driven by a 
chain drive off the pump shaft, this mechanism being necessary in order that the 
centrifugal pump might be charged when drawing its water supply from a dam, 
or any other source in which the water was not under pressure. 
Weight of Engines and Hquipment. 
No. 1 No. 2 
Tons cwt. Tons ewt. 
Carnyrirnlinoades: Mieke i ors! Se OOS Aa 4 134 
All equipment removed (except topladder) . 4 18 4 4 
Horse-power of the Engines. 
R.A.C. rating es. Eieteegoae 60°0 
