8 PHOTO-MICROGRAPHY 



mixed form of jet be employed, the coal gas must be so as well. The compressed gas, 

 whether oxygen or coal gas, is contained and stored in steel bottles, and as these 

 receptacles have to be of sufficient strength to sustain enormous pressure— which, as a 

 matter of fact, in a full-charged bottle is about eight times the amount employed in a 

 modern locomotive— it is necessary to say a few words about them. We strongly 

 advise every purchaser of one of these cyhnders to go to the headquarters of the 

 leading gas compressors in England— we refer to Messrs. Erin's, of Horseferry Road, 

 Westminster. Their cylinders may be considered absolutely safe, both for carriage 

 and use, because the company have made the most careful and exhaustive tests and 

 elaborate and costly experiments that can possibly be designed to ensure perfect 

 workmanship, perfect material, and perfect testing. No expense has been spared m 

 this department, and whether the customer orders it or not his cyHnder is periodically 

 overhauled and tested, being destroyed if showing the least signs of weakness. 



We regret to say that one London firm apparently does not feel bound by the 

 recommendation following the careful and rigorous investigations of the Board of 

 Trade, and has been known to send out cylinders made of metal which is positively 

 and absolutely condemned by the Board in question. This is a subject which should 

 occupy the attention of every lanternist and user of the limelight, and they should 

 avoid having anything to do with cylinders badly made. The only advice that can 

 be given in the matter, seeing it is impossible for a customer to analyse the steel of 

 the cylinder sent to him, is to have no compressed gas except from those who not 

 only conform with the regulations of the Board of Trade in question, but who mamly 

 were the investigators in the whole subject from the first. We refer to Brin's 

 Oxygen Co., of whom we have already spoken ; and in saying this it must be 

 distinctly understood the writer has no interest directly or indirectly in the company, 

 but mere ly makes this statement as a guide to those he is attempting by these 

 remarks to assist. 



One more point also should not be overlooked : seeing that the greatest danger is 

 caused by mixing oxygen and hydrogen unless in a properly appointed jet, so it is 

 exceedingly dangerous to have interchangeable cylinders, that is to say, those that 

 can be filled to-day with oxygen and to-morrow with hydrogen, for it is very obvious 

 that an explosive mixture may thereby be readily formed which, the instant the 

 unfortunate operator applies a light, causes an explosion hardly less terrific than that 

 of dynamite or gunpowder. 



Brin's Oxygen Co. have now for some years instituted a plan which utterly 

 prevents any possible accident of this description, for the oxygen cylinders have a 



