202 
ried out with that accuracy of detail which is, we 
believe, attained by the statistical department of the 
English Board. In this connection Prof. Heincke 
states (p. 66) :—‘*‘ The appendix to this report contains 
a number of these tables drawn up by me from the 
Erglish measurements. Close inspection will show, 
that here and there inaccuracies and errors have crept 
in during the preparation of the tables. Thus, in the 
case of large numbers which are the sum of many 
measurements, smaller or larger differences may be 
present between the English data and my _ tables. 
These small discrepancies will perhaps be excused, 
when the enormous amount of calculating work. is 
considered; I do not believe that any essential error is 
present, which might lead to erroneous conclusions.” 
In the opinion of the writer of this note there can be 
no excuse for a slovenly and inaccurate treatment of 
statistical data, and figures should not be published 
until errors such as those alluded to by Prof. Heincke 
have been eliminated. 
SURFACE COMBUSTION. 
URING his researches upon flame,? Sir Humphry 
Davy discovered, in 1817, that the constituents 
of a combustible mixture will combine slowly below 
the ignition temperature; this led him to inquire 
whether, seeing that the temperatures of flames far 
exceed those at which solids become incandescent, a 
metallic wire can be maintained at incandescence by 
the combination of gases at its surface, without actual 
flame. He thereupon tried the effect of introducing a 
warm platinum wire into a jar containing a mixture 
of coal-gas and air rendered non-explosive by an 
excess of the combustible constituents; the wire imme- 
diately became red hot, and continued so until nearly 
the whole of the oxygen: had- disappeared. 
During the twenty years which followed Davy’s 
discovery, several distinguished chemists (William 
Henry and Thomas Graham in this country, but more 
particularly Dulong and Thénard, and independently 
Débereiner in France) experimented upon the slow 
combination of gases at temperatures below the 
ignition point, in contact with hot solids, whereby it 
was established (1) that hot solids, and pre-eminently 
metals of the platinum group, have the power of 
inducing gaseous combustion. at relatively low tem- 
peratures; and (2) that hydrogen is, of ail combustible 
gases, the most susceptible to this action. 
The mechanism of this induced slow surface com- 
bustion formed the subject of a celebrated controversy 
between Faraday and De la Rive in 1834-5. De la 
Rive held the view that it consists essentially in a 
series of rapidly alternating oxidations and reductions 
of the surface; Faraday, on the other hand, contended 
that the function of the surface is to condense both 
the oxygen and the combustible gas, thus producing 
in the surface layers a condition comparable to that 
of high pressure. But, owing to lack of crucial ex- 
periments, no satisfactory theory of the phenomenon 
could be evolved, nor, with the exception of the famous 
‘‘Dobereiner lamp,”’ was there any practical outcome 
of this early work. In 1836 interest in the subject 
suddenly dropped, and was not revived for half a 
century. 
Meanwhile, the researches of Deville upon the dis. 
sociation of steam and carbon dioxide at high tem- 
peratures led to the notion, which was strongly upheld 
by the late Frederick Siemens, that inasmuch as incan- 
descent surfaces promote dissociation, they must neces- 
sarily hinder combustion. This, of course, is falla- 
cious; we now recognise that if, as Deville proved, 
1 From a discourse delivered at the 
February 27, by Prof. W. A. Bone, F.R.S. 
2 Collected Works, vol. vi., p. 8. 
NO. 23245) VOL.03 | 
Royal Institution on Friday, 
NATURE 
[APRIL 23, 1914 
an incandescent surface accelerates the dissociation of 
steam, it must, according to a principle enunciated by 
Ostwald, of necessity accelerate the combination of 
oxygen and hydrogen in like degree, provided always 
that the surface remains chemically unaltered. 
A notable demonstration of the possibility of realis- 
ing a flameless incandescent surface combustion in 
contact with metals other than those of the platinum 
group was given by Thomas Fletcher in a lecture at 
the Manchester Technical School so far back as 1887.° 
He injected a mixture of gas and air on to a large 
ball of iron wire, flame being used at first in order 
to heat the wire to the temperature necessary to induce 
a continuous surface combustion; on extinguishing 
the flame, by momentarily stopping the gaseous mix- 
ture, the combustion continued without any flame, 
but with an enormous increase of temperature. 
Fletcher grasped three important points, namely, (1) 
that ‘‘this invisible flameless combustion is only pos- 
sible under certain conditions’’; (2) ‘‘that the com- 
bustible mixture shall come into absolute contact with 
a substance at high temperature .. .’’; and (3) that 
‘‘in the absence of a solid substance at a high tem- 
perature, it is impossible to cause combustion without 
flame’’; but, so far as I am aware, he did not follow 
up the matter beyond this point, either in its theo- 
retical aspects or practical applications, and his work 
had but little influence upon contemporary opinion or 
practice. 
My own investigations upon surface combustion 
began in 1902 with a systematic attempt to elucidate 
the factors operative in the slow combination of 
hydrogen and of carbon monoxide in contact with 
various hot surfaces (e.g. porcelain, fire-clay, mag- 
nesia, platinum, gold, silver, copper, and nickel 
oxides, etc.) at temperatures below 500°. Into the 
details of these earlier experiments, which preceded 
and led up to the technical developments about which 
I shall speak later, I do not propose to enter; it will 
be sufficient for my present purpose if I say that it 
was proved beyond all question :—(1) That the power 
of accelerating gaseous combustion is possessed by all 
surfaces at temperatures below the ignition point in 
varying degrees, dependent upon their chemical char- 
acters and physical texture; (2) that such an acceler- 
ated surface combustion is dependent upon an 
absorption of the combustible gas, and probably also 
of the oxygen, by the surface, whereby it becomes 
‘“activated’’ (probably ionised) by association with 
the surface; and (3) that the surface itself becomes 
electrically charged during the process. Finally, cer- 
tain important differences between homogeneous com- 
bustion in ordinary flames and heterogeneous com- 
bustion in contact with a hot surface from a chemical 
point of view were established, so that there can be no 
longer any doubt as to the reality of the phenomenon.* 
If hot surfaces possess the power of accelerating 
gaseous combustion at temperatures below, or in the 
neighbourhood of, the ignition point, the same power 
must also be manifested in even a greater degree at 
higher temperatures, and especially so when the sur- 
face itself becomes incandescent. Indeed, there are 
experimental grounds for the belief that not only does 
the accelerating influence of the surface rapidly in- 
crease with the temperature, but also that the differ- 
ences between the catalysing powers of various sur- 
faces, which at low temperatures are often consider- 
able, diminish with ascending temperatures until at 
bright incandescence they practically disappear. 
Such considerations as I have thus briefly explained 
3 Journal of Gas Lighting, 1887, i, p. 168. 
4 Bone and Wheeler, Phil. Trans. Roy. Soc., 1906 (A. 206, pp. 1-67), 
also further (unpublished) results (tg05-12) in collaboration with Messrs. 
G W. Andrew, A. Forshaw, and H. Hartley, which are summarised in 
| Berichte der Deutschen Chem. Ges., 1913. 
