GUTTA-PERCHA 



769 



in travelling ; in other words, a tendency on the part of the powder, resulting 

 from the different size of its grain as compared with the grains of glass-dust, to resume 

 to a dangerous extent its explosive character; and there is little doubt that the 

 delicate surface of powder is liable to be sensibly affected and fouled by the protective 

 medium, while strong doubts are expressed as to the keeping qualities of the mixture, 

 which lengthy and careful experiments alone could solve. It would always be neces- 

 sary also, on service, to keep so large a supply of powder ready for immediate use as 

 to render quite insignificant the degree of additional security which might be afforded 

 by having the remainder non-explosive. The formidable objection to the process on 

 the score of its entailing a considerable amount of extra manipulation of gunpowder, 

 which would always be attended with more or less danger, delay, and uncertainty, 

 has never, that we are aware, been satisfactorily disposed of; and officers whose 

 opinions are entitled to every consideration object generally to a system which tends 

 to establish in men's minds a feeling of security about a substance which, however 

 harmless it may temporarily be rendered, must finally and frequently be handled in 

 its explosive form. 



How far, or how many of, these objections may apply to the process for civil use 

 cannot be decided without reference to the particular circumstances of each case ; but, 

 together, they certainly appear sufficiently formidable to preclude the employment of 

 the process for military or naval powders, either in transport or in store. 



An experiment made in 1866 in a martello tower near Eye, with five tons of 

 gunpowder rendered non-explosive by the process proposed by Mr. Gale, attracted 

 sufficient attention to render acceptable these few words on the rationale of this so- 

 called discovery and its probable value for military or other purposes. 



The magnitude of the Eye experiment gave it a specious importance, to which it 

 had no real claim. But when five tons of gunpowder are seen slowly burning away 

 without any explosive effect, it is difficult to make people understand that a great 

 practical result has not been achieved. And this was the sight by which visitors 

 to Pett Level near Eye were rewarded. Five tons of cannon powder had been 

 mixed with twenty tons of glass-dust, and stowed in barrels in the magazine and 

 on the basement-floor of a martello tower. An attempt was first made to cause an 

 explosion or a conflagration by firing one barrel, and when this failed, a sort of bonfire 

 was ignited within the tower, which rapidly communicated from barrel to barrel, and 

 burnt steadily, with a dense acrid smoke from the door and windows of the tower. 

 But there was no explosion nothing more than an occasional dull, muffled puff as the 

 contents of a fresh barrel caught fire. 



The experiment placed beyond doubt the efficiency of the method of protection pro- 

 posed, even for a large mass closely stowed in a confined space ; but it left the 

 question of the wisdom of adopting that particular method precisely where it was 

 before. 



The above remarks, which completely embrace the question, are borrowed from an 

 excellent article in the ' Pall Mall Gazette.' Little need be added to them. It will 

 be gathered from the first paragraph that the gunpowder is not rendered really non- 

 explosive, but that its rate of combustion is retarded. Confined in a cask or any 

 vessel preventing the escape of the gases formed, the result would be, after a little 

 time, an explosion. 



This_ mixture of powdered glass with gunpowder has been recommended also for 

 protecting gunpowder from damp ; it having been forgotten that all porous bodies, 

 and powdered glass especially, have the property of condensing moisture from the 

 atmosphere within their pores. 



Our gunpowder Exports have been as follow: 



GUNPOWDER, GERMAN. See EXPLOSIVE AGENTS. 



GOTTPOWDSR, WHITE. See EXPLOSIVE AGENTS. 



GUTTA-PERCHA. Although the trees yielding this substance abound in the 

 forests of the Indian Archipelago, the first notice taken of it appears to have been 

 by Dr. W. Montgomerie, in a letter to the Bengal Medical Board, in the beginning of 



VOL. II. 3D 



