500 British Association for the Advancement of Science, 



Dr. Martin Barry communicated the result of some observations 

 on the colour of the sky, as seen from the summit of Mont Blanc ; 

 and expressed his conviction, that, while the depth of this colour 

 appeared very much increased, as might be expected, from his ele- 

 vated position, its peculiar tinge of black was in a great measure 

 due to the contemporaneous reception by the eye of rays from the 

 snow. He stated that the same effect has been observed by Boussin- 

 gault in his attempted ascent of Chimborazo and other mountains. 



Cursory Remarks upon some matters contained in a Letter addressed 

 by Mr. William Hamilton to Mr. Packenham. By William 

 Schiede, M.D. (Translated by Mr. Hamilton.) 



1. The Oxalis tuberosa is a plant of Chili, not of Mexico; at 

 least I have never heard of any plant of this genus with esculent 

 roots being cultivated in the Mexican republic. The country 

 abounds in wild species of Oxalis (the Xoxocayallin of Hernandez), 

 some of which are applied to culinary purposes in the same manner 

 as the sorrels (Rumex) of Europe. 



2. The Solanum tuberosum is, without doubt, a native of this soil, 

 as has been already published in the beginning of 1829. I have 

 collected several varieties, which may, perhaps, prove to be distinct 

 species. Moreover, I have collected among them one species (So- 

 lanum oxycarpum, Schiede) equally tuberous, and in every respect 

 akin to the S. tuberosum, from which it differs in bearing pointed 

 fruit Notwithstanding which, the Papa, according to my researches, 

 has no Aztec name, being known to the Aztecs by the name of 

 Papa. Hernandez speaks of the Peruvian Papa; which proves how 

 little he was aware of its being a plant of this country. 



3. According to my observations, the Cevadilla is a new plant 

 ( Veratrum officinale, Schiede). Hernandez has described and fi- 

 gured it very indifferently under the name of Hzcuinpatli, or Dog- 

 killer. It is a powerful anthelmintic, diuretic, antiarthritic, and an- 

 tipsoric. I am not aware of its having been employed in the cure 

 of hydrophobia. In the course of the last ten years a new species 

 of Veratrum ( V. Orfilia, Sabadilla,) has been published by Des- 

 courtilz, which he conjectures to be the plant which yields the ce- 

 vadilla of the shops of Europe. In my opinion, this last plant is 

 doubtful, and is at least distinct from the Cevadilla of this capital 

 and of the shops of Berlin. 



4. I am not acquainted with the plant called Amole, of the pro- 

 vince of Sonora. A root is exposed for sale in the market-place of 

 Mexico, under the name of Amole, which is the Agave polyan- 

 tkoides of Schiede, or at least one nearly related to it. It is com- 

 monly used for washing linen, in place of soap, as it abounds in an 

 extractive and saponaceous principle. 



5. I do not know the Cestrum Mutisii. If I mistake not, it is a 

 production of South America. In some parts of Mexico they em- 

 ploy in its place the sap of the Justicia tinctoria ; but I cannot say 

 whether or not its colour is as durable as that of the Cestrum, hav- 



