306 



Which two latter compounds are isomeric with oleamide and ricino- 

 lamide. 



The melting points of these amides were found as follows : — 



Margaramide, , . . . 103° C. (60° C. BouUay) 

 Palmamide and Elaidamide, 94° C. 

 Oleamide, 8:^° C. 



The author considers the melting points ascribed to ricinolamide 

 {dQ"" C.) and isocetamide (67° C), by Boullay, are below the truth. 



The researches of the author are not yet completed, and the re- 

 sults of experiments now in progress will be given on a future occa- 

 sion. 



Monday, IQth April 1855. 



Right Rev. Bishop TERROT, V.P., in the Chair. 



The following Communications were read : — 



1. Notice of some new Forms of British Fresh- Water 

 Diatomacese. By William Gregory, M.D., F.R.S.E., Pro- 

 fessor of Chemistry. 



The author stated that he had examined, more or less minutely, 

 nearly 300 fresh-water gatherings, and that he had found in these 

 very nearly all the known British species, besides a number not yet 

 described. He mentioned that, from the want of figures, it was often 

 difficult to know whether a form were new or not. Thus, Pinnularia 

 latestriata, found by the author two years since in the Mull earth, 

 had been considered as a new species by all British naturalists, as 

 well as several foreign ones ; yet in Ehrenberg's last work, " Mikro- 

 geologie" it is figured as P. borealis, and as having been described 

 by Ehrenberg ten or twelve years ago. The papers of that author, 

 in the Berlin Reports and Transactions, are not generally accessible. 

 Ehrenberg describes this species as being one of two found scattered 

 in every part of the world, and in almost every locality, more uni- 

 formly than any others ; which is confirmed by the author's observa- 

 tions in this country. Yet, although a remarkable and conspicuous 

 form, it had escaped notice in Britain till 1852. This shows the 

 necessity of minute search, without which the scattered forms are 

 sure to be overlooked. 



The new forms were described in three sections. 



