202 
MINUTES OF PEOCEEDINGS OF 
Shot of these descriptions have been tested both at Portsmouth and 
Shoeburyness; Captain Key considers the order of merit to be as follows 
(1) Dr Price’s. (2) Laboratory. (3) Service. 
And the Special Committee on Iron in their Report of 1863, thus refer to 
this subject:— 
“ Attempts have been made to improve the quality of cast-iron for this purpose. 
Col. Boxer, Dr Price, and Capt. Palliser have each produced metal much better 
than that ordinarily in use, and these improvements can, if required, be applied at 
a very slight additional cost.” 
The service cast-iron shot are, as is well known, cast in sand, but Major 
Palliser, late of the 18th Hussars, proposed that thick iron moulds should 
be used for the purpose. This method of casting has the effect of hardening 
the shot to a considerable extent, provided a proper description of pig iron 
is used. 
Dr Percy thus alludes to chill-casting:—- 
C£ The mode of existence of carbon in non is in great measure determined by the 
conditions of solidification after complete fusion, and the temperature at which 
fusion has been effected. Rapid 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 contact 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.” 
The first experiment which was made on the suggestion of this officer was 
with 12-pr. shot, in November 1863, and the opinion of the Committee on 
the result obtained on that occasion is thus recorded,— 
“ The chilled 12-pi\ shot which were manufactured in the Royal Laboratory on 
the plan proposed by Captain Palliser, all broke up on impact, but they showed a 
marked improvement on the common cast-iron shot of the service, the indent of 
which on a 2J-in. plate is 0-75", whilst an average of four shots of chilled cast-iron 
gives an indent of 2*, and in two instances the 2-I" plate was broken through by 
these shot.” 
The experiments since made with 7" and 9*2" cylindrical shot quite 
confirm the favourable results which w T ere obtained from the 12-pr. shot; but 
two points still remain for determination regarding shot of this nature, viz. 
the description of pig iron best suited for chilling; and also how mnch of 
the success which has attended the use of Major Palliser’s shot is due to 
the chilling process, and how much to the use of improved pig iron. With 
reference to the first point Major Palliser tells me that he has found in the 
case of Pontypool iron that No. 1, or the softest brand, only chills to a 
depth of about Jth of an inch ; No. 2 to about Jth, whilst a spherical 9" 
shot of No. 6 was chilled to the centre. Some of the soft Scotch iron will 
not chill at all. 
