PREVENTION OF SMOKE. ~ 345 



We have already used phosphorus in an experiment which showed its great 

 affinity for oxygen. By boiUng it with a strong solution of potassic hydrate a 

 mixed phosphureted hydrogen is set free which is spontaneously combustible. In 

 practice it is made to bubble through water, and each bubble as it bursts produces 

 a flash and spontaneous combustion. In oxygen the explosion is very violent. 

 This gas has a special interest, as the ignis fatuus has been explained by it — 

 whether truthfully or not is not certain. It is one of the most beautiful exhi- 

 bitions of spontaneous combustion in all chemistry. It is susceptible of many 

 modifications. 



As a finale I propose to exhibit to you fire under water. We select as two 

 suitable substances phophorus and chlorate of potash. These are placed in the 

 bottom of a flask and water poured over them. To start and maintain the com- 

 bustion we add sulphuric acid. A highly oxidizing compound is formed, and 

 the phosphorus begins oxidizing or burning with a bright light. To make it more 

 beautiful we can add phosphide of calcium, when, in addition to the white glow 

 of the phosphorus, we have an elegant emerald green glow added to our fire 

 under water. It is not a safe experiment by any means, as there is danger of 

 breaking the vessel by the violent heat caused by the reaction. — Scientific Amer- 

 ican. 



PREVENTION OF SMOKE. 



At a meeting of the Society of Engineers, held on Monday evening, June 

 13th, a paper was read by Mr. A. C. Engert on the " Prevention of Smoke." 



The author, in choosing the title of the " Prevention of Smoke," instead of 

 the " Consumption of Smoke," gives it as his opinion that smoke, once produced 

 by the atmosphere and while being carried by the air, cannot be consumed, as 

 every particle is surrounded by a thin film of carbonic acid. When, however, 

 smoke is condensed as soot, heat will liberate the carbon from the acid, and then 

 the former will burn rapidly. If this theory is found to be correct, carbon can- 

 not destroy the germs of disease floating in the air. 



For the consumption of smoke, many ingenious and elaborate inventions are 

 on record, but not yet adopted on account of expense and complexity of mechan- 

 isms. A simpler apparatus is, therefore, required. 



To prevent smoke, the cold air must not be allowed to come in contact with 

 the gases arising from green coals, and, for this purpose, the furnace is, so to 

 speak, divided into two parts. The fire-door is removed from the boiler, and a 

 box fixed on in front. On each side of this box rails are placed inside, on which 

 a plate or shutter may rest, which can be pushed forward or backward as re- 

 quired. When pushed forward it passes within the boiler and drops over the 

 fire bars some eighteen inches, thereby cutting off the draft and preventing the 

 condensation of the gases arising when fresh coals are put on, thus preventing 

 smoke and the cooling of the boiler. 



