PRaCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 303 



The subject was further discussed by Messrs. Seeley, Roosevelt and Enos 

 Stevens. 



A desire having' been expressed to examine the question of combustion 

 in all its bcaringcs, the subject of " Fuel" was selected for the next meeting. 



Adjourned to Thursday, May 19. 



..-VSlliKlCAN liNSTirUit; ruL 



May I9th, 1864 

 Chairman, Prof. S. D. Tillman; Secretary, Mr. B. Garvey 



Americ.w Institute Polytechnic Association, ) 



Prizes for Roof Constructions of Wood and Iron. 



The Secretary read a communication from the Austrian Engineers' Union, 

 at Vienna^ containing an offer of prizes for the best and second best treatise 

 on the most useful " roof constructions of wood and iron," to be illustrated 

 with the necessary drawings, nil on the same scale. For estimating the 

 stability of each structure, under varied contingent weights, all the 

 requisite scientific rules and formulas are to be set forth. There should 

 also be given the results of calculations and comparisons, in convenient 

 tables, so placed together that the architect or engineer can find the neces- 

 sary data for making the estimates for each roof construction separately. 

 The competitors will have until September 30, 1865, to send in their works. 

 The successful authors, in addition to the prizes, will be entitled to the 

 copyright of their works, provided they publish them within six months. 

 After that time, should they decline to publish, the Austrian Engineers' 

 Union charges itself with the publication of the two treatises in a suitable 

 manner. Further information concerning this offer of prizes may be 

 obtained by applying to the Secretary of the American Institute. 



The presiding oflScer presented the following interesting summary of 

 scientific experiments and discoveries : 



Meg ASS a Disinfectant. 



Dv. II. G. Dalton, of Demerara, has proved by experiment that megass 

 or begasse — the dried stem of tire sugar-cane after its saccharine juice has 

 been extracted by pressure — has the property of absorbing or destroying 

 the noxious elHuvia arising from animal decomposition. He has used it as 

 a disinfectant in a hospital where, except in the immediate neighborhood 

 of the worst cases of ulcers, there was no unpleasant odor, and even there 

 the disagreeable smell was greatly modified. 



The Most Volatile Constituents of Petroleum. 



Mr. Edmund Ronolds lately stated before the Royal Society of Edin- 

 burgh that the gases dissolved in Pennsylvania petrohium, and which give 

 it such a high degree of inflammability, were composed of the lower ni'ira- 

 bers of the marsh gas series. Gases taken from the surface of the liquid, 

 as imported in casks from America, were shown by endiometrical analysis 

 to contain a mixture of nearly equal proportions of the hydrides of ethyl 

 and propyl. The same compounds were found in the gases evolved on 



