190 TRANSACTIONS OF THE 



iron grating for its purification, into a vacant upper chamber, 

 thence it is conducted by an iron pipe into the condensing box. 

 This iron pipe, passing through the cover of tlie condensing box, 

 descends below, and discharges the gas into the water of the con- 

 densing box. Thence it rises into the vacant chamber above the 

 water, before it finds its exit, and thence into the gasometer ready 

 for use. 



The material used is an oil from rosin, though not what is com- 

 monly called rosin oil. It is an earlier, cheaper and better product 

 of collophony, decomposable at a lower and therefore a more eco- 

 nomical degree of heat. There cannot be found in the whole 

 range of chemistry a compound more richly laden with illumi- 

 nating qualities, or yielding gases more innocuous in respiration, 

 or less injurious to furniture, for it contains neither carbonic acid 

 nor sulphurated hydrogen. 



The supply of this material is inexhaustible, and any anticipated 

 demand can scarcely enhance the price. It is now delivered at 

 the company's works, in New-York, at eighteen cents per gallon. 

 Each gallon of the raw material may be safely estimated to make 

 one hundred cubic feet of gas from this machine. The apparatus, 

 as above described, with a gasometer of the capacity of 300 cubic 

 feet, will contain an average of a week's supply to an ordinary 

 family the year round, and is sold at the company's works in New- 

 York, complete for $350. They are made, however, of any 

 required capacity, and adapted in form and size to the necessities 

 of the space they are to occupy, and the requirements of the 

 burners they are to gratify. These requirements and necessities 

 are so varied, and so materially increase or lessen the cost of the 

 whole machine, that it is impossible to furnish, as the company 

 are often asked to do, a tariff of prices for the various sizes. The 

 cost of any sized machine can always be had by application at the 

 office of the company, in person or by letter, or by application to 

 either of the general agents of the company. Such application 

 should always be accompanied with a statement of the quantity 

 of gas to be consumed each night, and the number of nights 

 required to be supplied. 



The quantity of gas can be readily estimated, basing the calcu- 

 lation upon a consumption of two and one-half cubic feet per 



