167 



March 18, 1857. 



Dr. C. T. Jackson, Vice-President, in the Chair. 



Dr. A. A. Hayes reported that the specimen of linseed oil 

 which was referred to him at the last meeting, had been tested. 

 It was found to be slightly acid, in consequence of well-known 

 reactions taking place between a minute quantity of fermentable 

 matter expressed from the seed and the oil, resulting in the pro- 

 duction of an oily acid. Tlie oil is not, however, in the state 

 which it assumes on exposure to air, but closely resembles fresh- 

 drawn oil, in all respects but odor and slight acidity. When 

 boiled as usual, it becomes capable of forming the elastic film 

 after exposure to air, and its useful properties have not been lost 

 or impaired after its long submersion in sea water. 



In answer to a question from Mr. Mills, as to the composition 

 of pudding-stone, Dr. Hayes replied that he had made a some- 

 what extended examination of the cementing material of the 

 Roxbury conglomerate, and found that it is silicate of lime gen- 

 erally. There are cases where finely-divided slaty argillite 

 forms, with silicate of lime, quite large quantities of cement, 

 uniting pebbles of considerable size ; but these exhibitions are 

 only another feature, referable to the action of the same silicious 

 compound. The rock contains chlorine, and as chloride of 

 calcium is readily decomposed by hydrous silica, it might be 

 assumed that the silicate of lime was thus formed. But the con- 

 glomerate is very frequently traversed by bold dykes of trap, 

 which contain a large amount of sulphuret of iron, and the fissures 

 in the conglomerate, being often filled with sublimed quartz, the 

 more probable supposition is, that the silicate of lime was formed 

 by the transportation of silica in the heated vapor of water. 

 Such silica would combine with the lime and alumina of the 

 comminuted slates, and form the cement at the points where we 

 now find it. 



In reply to a question, Dr. Hayes expressed as his conclusions, 



