THE ROYAL ARTILLERY INSTITUTION. 
231 
P ALLIS EK’S (CHILLED) SHOT AND SHELL. 
BY CAPTAIN VIVIAN DBE.ING- MAJENDIE, E.A. 
ASSISTANT SUPEEINTENDENT, EOYAL LABOEATOEY. 
Chilled projectiles have attracted considerable attention since they were 
first brought forward in 1863, by Major (then Captain) Palliser, of the 18th 
Hussars; but they have lately derived additional interest and importance 
from the remarkable results which have attended the more recent expert 
ments, and from the fact that they are now definitely adopted for battering 
purposes.* 
The following paper, in which the origin, nature, and practical value of 
chilled projectiles are discussed, has been drawn up with a view to replying 
to the various enquiries which have been addressed to me on the subject* 
and of satisfying further enquiry by anticipation. 
The different character of castings obtained from sand and metallic moulds, 
respectively, has long been known; and is thus explained by Dr Percy in a 
passage quoted by Captain Harrison in a former No. of these “ Proceedings.”t 
“ The mode of existence of carbon in iron is in great measure determined by 
the conditions of solidification after complete fusion, and the temperature 
at which fusion has been effected. Eapid solidification favours the retention 
of carbon in the combined state, and by this means it is possible to convert 
characteristic grey*iron into perfectly white iron. Thus by pouring liquid 
grey cast-iron into a cold metallic mould, so as to cause the most sudden 
cooling possible the exterior of the solid iron, where it comes in direct con¬ 
tact with the mould, will be found to be in the state of white iron, while the 
interior will be in the state of grey-iron. This principle is extensively 
employed in practice, in the process known as chill-casting. It is adopted 
when it is desirable to render the surfaces extremely hard, white iron being 
intensely hard, as compared with grey-iron. 1 ” To this passage I would 
draw particular attention, for it contains the rationale of “ chill-casting” or 
“case-hardening;” further calling attention to the fact that white iron, 
which is not normal cast-iron, but to a certain extent an exceptional product 
of the furnace, differs chemically from grey or “ foundry ” iron principally 
in the condition of the carbon which it contains : in white iron, the carbon 
is in a combined state; in grey iron it is generally uncombined, being mechani¬ 
cally diffused through the mass in the form of graphite, the amount of carbon 
not necessarily differing materially in either. 
* W. O. Letter, 26th October, 1866, intimated, “the adoption of chiHed iron as the material 
for projectiles required in the service for battering purposes.” 
f Vol. IV. p. 202. 
[VOL. V.] 
31 
