218 PROCEEDINGS OF THE AMERICAN ACADEMY 



tallized in needles which were permanent in the air, but lost in weight 

 over sulphuric acid. 



I. 0.4924 grm. of the air-dried salt lost at 80° 0.0099 grm. H,0. 

 II. 0.8678 grm. of the air-dried salt lost at 80° 0.0248 grm. U^O. 



III. 0.4794 grm. of the anhydrous salt gave, on ignition with HjSO^, 



0.1001 grm. CaSO,. 



IV. 0.8266 grm. of the anhydrous salt gave, on ignition with HjSO^, 



0.1707 grm. CaSO^. 



Argentic Trihromacrylate, AgCgBi-gOg. The silver salt is precipi- 

 tated when argentic nitrate is added to an aqueous solution of the 

 acid, but is more readily prepared from a solution of the acid in 

 diluted alcohol. The salt is tolerably stable, and crystallizes in small, 

 six-sided plates. 



0.5267 grm. of the salt gave 0.1848 grm. AgCl. 



Calculated for AgCjBraOj. Found. 



Ag 25.96 26.40 



Mr. Mabery has undertaken the study of the clilorbromacrylic and 

 diiodbromacrylic acid, and will present the results of these investiga- 

 tions in a separate paper. 



Theoretical Considerations. 



Schmelz and Beilstein,''' from a comparison of the formula of mel- 

 litic acid, C^H^O^ (as it was then written), with that of mucobromic 

 acid, C^HgEPj^Og, were led to suspect a close connection between the 

 two ; but their investigations undertaken with the hope of proving 

 this point yielded negative results. 



In 1869, Limpricht t suggested that a series of compounds, among 

 which were furfurol and its derivatives, contained a ring of four car- 

 bon atoms, and that they were therefore derived from an hypothetical 

 hydrocarbon, — 



* Ann. Chcni. u. Pliarn., Suppl. iii. 280. 



t Berichte der deutsch. chem. Gesellsch., ii. 212. 



