766 CHARCOAL 



ftel, but it produces BO much ash as to make its use very objectionable. 100 pounds 

 of dry peat, say Messrs. Ronalds and Richardson, leave 21 Ibs. of ash, and pro- 

 duce 47 Ibs. of charcoal, therefore those 47 Ibs. of peat charcoal will contain 21 Ibs. or 

 45 per cent, of ash. 



Rogers adopted in Ireland a system of drying peat and carbonising it, -which was 

 for some time carried forward with much promise of success. Green produced a 

 draught of hot air through a drying house, by means of chimneys and fires. He then 

 distilled the dry peat in wrought-iron cylinders, similar to those employed in making 

 illuminating gas, the gases obtained being used as part of the fuel below. Notwith- 

 standing all the attempts which have been made to utilise peat charcoal, there is no 

 process now carried out on a large scale. 



PLATINISED CHARCOAL. This preparation, which appears destined to become ex- 

 ceedingly valuable, was introduced by Dr. Stenhouse, who thus describes the modo 

 of preparation and some of its uses : 



' The lighter kinds of wood charcoal, owing to the nine volumes of oxygen gas 

 contained in their pores, possess a considerable power of oxidising the greater 

 number of easily alterable gases and vapours. The absorbent power of charcoal, 

 however, is comparatively much greater than its capacity for inducing chemical 

 combination. In this respect charcoal presents a remarkable contrast to spongy 

 platinum, which, though inferior as an absorbent for some gaseous substances such 

 for instance, as ammonia, of which spongy platinum absorbs only 30 volumes, while 

 charcoal absorbs ninety is, nevertheless, immensely more effective, both as an 

 oxidiser, and as a promoter of chemical combination generally. As it is desirable 

 for some purposes, while retaining the absorbent power of charcoal unimpaired, to 

 increase its oxidating influences, it struck me that this important object might be 

 easily effected by combining the charcoal with minutely-divided platinum. In this 

 way, a combination is produced, to which I have given the name of platinised char- 

 coal, which possesses the good properties of both of its constituents. In order to 

 platinise charcoal, nothing more is necessary than to boil the charcoal, either in 

 coarse powder or in large pieces, in a solution of bichloride of platinum, and when 

 the charcoal hai? become thoroughly impregnated with the platinum, which seldom 

 requires more than ten minutes, or a quarter of an hour, to heat it to redness in a 

 close vessel a capacious platinum crucible being very well adapted for this purpose. 

 When 150 grains of charcoal were impregnated with nine grains of platinum, by the 

 process just described, the charcoal was found to have undergone no change in its 

 external appearance, though its properties have been very essentially altered. When 

 a few grains of this platinised charcoal were passed up into a mixture of dry oxygen 

 and hydrogen in the proportions to form water, over mercury, the two gases com- 

 bined in the course of a few minutes, precisely in the same way as when a clay 

 ball of spongy platinum is employed. When, however, a fragment of charcoal con- 

 taining a considerably larger proportion of platinum was passed up into a similar 

 gaseous mixture, the gases instantly combined with explosive violence, just as if 

 platinum-black had been used. If pieces of cold platinised charcoal are held in a jet 

 of hydrogen, they speedily become incandescent, and inflame the gas. Platinised 

 charcoal, when slightly warmed, likewise rapidly becomes incandescent in a current 

 of coal-gas, but the jet of gas is not inflamed, owing to the very high temperature, a 

 white heat, which is required for this purpose. 



1 In the vapour of alcohol or wood spirit, platinised charcoal becomes red hot, and 

 continues so till the supply of vapour is exhausted. In the course of a few hours, 

 spirits of wine, in contact with platinised charcoal and air, is converted into vinegar. 

 I find that two per cent, of platinum is sufficient to platinise charcoal for most pur- 

 poses. Charcoal containing this small amount of platinum, causes a mixture of 

 oxygen and hydrogen to combine perfectly in about a quarter of an hour, and this 

 is the strength of platinised charcoal that seems best adapted for charcoal disinfectant 

 respirators. Charcoal containing one per cent, of platinum causes a mixture of 

 oxygen and hydrogen to combine in about two hours ; and charcoal containing the 

 extremely minute quantity of per cent, platinum, produces the same effect in from 

 6 to 8 hours. Platinised charcoal seems likely to admit of various useful applications ; 

 one of the most obvious of these is its excellent adaptability to air-filters and re- 

 spirators for disinfectant purposes. It is plain that no easily alterable organic vapours, 

 Buch as effluvia or miasmata, can remain in contact, even for a few minutes, with 

 platinised charcoal without being destroyed, their carbon being converted into carbonic 

 acid, and their hydrogen into water. 



' Platinised charcoal also seems likely to prove a highly useful application to malig- 

 nant ulcers and similar sores, on which I confidently expect, from its powerful 

 oxidating properties, that it will act as a mild, but effective, caustic. Perhaps, how- 

 ever, as an application to sores, platinised asbestos, either alone, or in combination 

 with platinised charcoal, might be found more manageable. In those diseases also 



