46S French Acade^ny. \ 



pour is liquefied by cold, and becomes coloured ; he might without 

 doubt by a cold more intense have crystallized it. You will re-J 

 collect that in tlie report of mv experiments with a cold of 58° R. 

 J observed that the nitric and muriatic acids, in congealing, pro- 

 duced two sorts of crystalline concretions, which when liquefied 

 take a red colour in the nitric acid and a greenish in the muriatic. 

 I mentioned fiirther, that sulplunic acid dashed with nitric va- 

 pour, loses its colour before congealing, and recovers it on being 

 liquefied : that colour is considerably deepened wlwn tbe fuming 

 sulphuric acid is heated in close vessels. I propose during this 

 winter to submit to the same degree of 58R. the different com- 

 pound gases; for which purpose I have still all my apparatus and 

 a great store of muriate of lime. 



M. Virey in a communication to the French Academy of 

 Sciences (formerly the Institute) states that the spur of the rye 

 is not a champicrnon of the genus Scleral icum, as M. Decan- 

 doUe had endeavoured to prove ; but that it is a real disease of 

 the grain ; since there are to be found in it all the peculiarities 

 of organization of the rye, a degeneration as j'et unknown in 

 its nature, amylaceous fecula, and probably all the immediate 

 materials of the Cerealia, 



Messrs, Beauvois, Thouin, and Thenard have also made a re- 

 port to the Academy on two papers of M. Dupetit Thouars, 

 relative to the effect produced by frost on flowers and young 

 shoots. M. Dupetit Thouars seems, according to the report, to 

 have been the first who perceived a small icicle even in the sub- 

 stance of the calyx of some flowers ; l)ut almost all botanical 

 authors had already noticed this phaenomenon in the young 

 buds, " In spring," observes M. Senne!;ier, " the new shoots of 

 the ligneous plants are extren)ely tender, humid, and full of 

 aqueous juices : the frost th.en destroys them with the herbaceous 

 plants, because the warn- which is frozen occujiies a greater 

 space than in the fluid form. Its sudden e:?pansion destroys the 

 frail organization of the vessels which contain this water : but 

 these alterations are more or less disastrous, according to the 

 nature of the organs, and their parts. Thus, if those organs and- 

 those fibres were susceptible of a great expansibility, if they were 

 at the same time very elastic, and that they could resume their 

 first state as soon as the water thawed,- then the dilatation of the 

 water changed into ice will dilate the organs of the plants, and 

 they will resume their first form, without having preserved any 

 apparent trace of alteration." The committee are of opinioii 

 that in this way we may accouiit for the little action which 



frosts^ 



I 



