546 HITCHCOCK: Mexican grass 



The microscopic examination of the samples was made by 

 H. K. Merwin of this Laboratory, 



RECAPITULATION 



Under certain conditions steam is capable of oxidizing iron and 

 its lower oxides to magnetite, Fe304, or to ferric oxide, FcoOs. 

 This fact has often been quoted as an indication of the probable 

 oxidizing action of steam upon lava during volcanic activity. 

 In this paper this reasoning from analogy is subjected to the 

 light of recent investigations and found wanting. In addition, 

 some experimental results are given which confirm the view that 

 the ferrous iron is not thus oxidized, and indicate that the pres- 

 ence of much ferrous iron in the lava and much steam in the 

 volcanic emanations of Kilauea are two facts which are in full 

 accord. Several miscellaneous experiments are also reported 

 which show that in the experimental study of the chemistry of 

 the lavas careful attention must be paid to the character of the 

 gas phase in contact with the lava if results of value are to be 

 obtained. The bearing of these experiments upon the interpre- 

 tation of the results obtained by pumping gases from rocks at 

 high temperatures need only be mentioned. 



BOTANY. — History of the Mexican grass, Ixophorus unisetus. 

 A. S. Hitchcock, Bureau of Plant Industry. 



In 1 791 Thaddeus Haenke, a Bohemian botanist accompany- 

 ing Malaspina on an exploring expedition to the Pacific coast 

 of America, visited Mexico, stopping at San Bias and Acapulco. 

 From the latter place he visited the interior of the country. 

 His collections were sent to Prague and were examined by the 

 botanists J. S. Presl and C. B. Presl, who finally published an 

 account of a few famihes, including the grasses,^ under the title, 

 Reliquiae Haenkeanae. In this work 15 genera and about 250 

 species of grasses were described as new. They came from the 

 western coast of South America, Panama, Mexico, Monterey 

 (California), Nootka Sound (Vancouver Island), and the Philip- 

 pine and Marianne Islands. Some of the species, supposed to 

 be new, proved to be the same as others previously described, 



1 Presl, Rel. Haenk. i: 207-349, pi. 37-48. 1830. 



