444 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



An explanation given of this is tliat tlie gases which exert this influence 

 have an attraction for oxygen, and are themselves undergoing a slow oxidation 

 at the same time. 



When two oxrdable bodies are in ^contact, one of them often takes prece- 

 dence in combining with oxygen, to the entire exclusion of the other. 



Phosphorus matches are usually made by melting phosphorus in water at 120 

 degrees, and adding a requisite proportion of chlorate or nitrate of potassa, 

 which is dissolved in this water, and if metallic oxides are used, or binoxide 

 of manganese or sesquioxide of lead, these are added, and then enough gum 

 to thicken the liquid. The whole is well triturated till the globules of phos- 

 phorus cease to 'be visible, and the mass is colored with Prussian blue or red 

 with sesquioxide of lead. The points of the sticks already sulphured are 

 dipped into this paste, and then cautiously dried in a warm chamber. The 

 object of the chlorate, nitrate or oxides is to promote the combustion of the 

 phosphorus, and that of the sulphur to ignite the stick, and the gum to form 

 a varnish which defends the phosphorus from oxidation till the surface i^ 

 abraded. 



Phosphorus is susceptible of four different degrees of oxidation, the high- 

 est of which is a powerful acid, while the acid property is not absent in the 

 lowest. These compounds are : 



Oxide of phosphorus . 2 P.-j-O. 



Hypophosphorus acid P.-}-0. 



Phosphorus acid P.-)-oO. 



Phosphoric acid. P.-|-50. 



Amorphous phosphorus ,may be obtained by several processes. A ready 

 one consists in heating phosphorus with a small quantity of iodine. The 

 amorphous phosphorus is separated from phosphorus in its ordinary condition 

 by treatment with bisulphide of carbon, which dissolves the latter and not 

 the former. 



After selecting "The Manufacture of Sugar" as the subject for the next 

 discussion, the Association adjourned. 



American Institute Polytechnic Association, I 

 December 22d, 1864. j 



Prof. Samucd D. Tillman, Chairin;in; Benjamin Garvey, Secretary^ 



Roasting Coffee. 



The first article exhibited was an automatic coffee roaster. Mr. S. B. 

 Ward stated that it was the invention of a physician who saw the necessity 

 of g'iviiig uniformity and expedition to the operation of roasting- coiFee. 

 The machine now presented, consisted of a wire gauze cylinder, tvhich 

 revolved in a cast iron frame, the whole, wdien placed on tup of a cast 

 iron cooking stove or range, was enclosed in a tin cover. When the coffee 

 is i)laced in the cylinder, by moving a stop-key, the cylinder begins to 

 rotate, and continues until the loasting is completed. The effect of this 

 rotary motion is to present ever}' berry to the beating surface for about 

 the same length of time. The power used is a spring which is connected 



