ATMOSPHKFaC AlB AS TIIK FOOD OF PLANTS. 93 



of fuel is tlioroui;l)ly ignited. When, on tlic other liaiid, tlic fire is cov- 

 ered witli cold fuel, carbonic oxide escapes copiously into the atmos- 

 phere. 



When crystallized oxalic acid is heated with oil of vitriol, it yields 

 water to the latter, and falls into a mi.Kturc of carbonic acid and carbonic 

 oxide. 



0.112 04, 2HsO = CO.i + CO + 3H,0. 



Carbonic oxide may, perhaps, be formed in small quantity in the de- 

 cay of ori,^anic matters; though Coren winder {Coinpt. Semi., LX, 103) 

 failed to detect it in the rotting of manure. 



ISel:iti«n<« of <'arl»«iiic Oviclo lo Ves^etation. — Ac- 

 cording to Saussure, while pea-[ilant< languish and die when immersed 

 in carbonic oxide, certain marsh plants {Kpilobium Mrsutum, Lythrum 

 salicaria, and Fbhjgonum peisi carlo) flourish as well in this gas as in com- 

 mon air. Saussure's exi^eriments with these plants lasted six weeks. 

 There occurred an absorption of the gas and an evolution of oxygen. 

 It is thus to be inferred that carbonic oxide may be a source of carbon 

 to aquatic plants. 



Boussinuault (Compt. Rend., LXI, 493) was unable to detect any action 

 of the foliage of land plants upon carbonic oxide, either when the gas 

 ■was pure or mixed with air. 



The carbonic oxide which Boussingault found in 18G3 in air exhaled 

 from submei-ged leaves, proves to have been produced in the analyses, 

 (from pyroii-allate of potash.) and was not emitted by the leaves them- 

 selves, as at first supposed, as both Cim-z and Boussingault have shown. 



j^'itroux Oxide, NoO.— This substance, the so-called laiig/ivig 

 gas, is i)repared from nitrate of ammonia by exposing that salt to a heut 

 somewhat higher than is necessary to fuse it. The salt decomposes into 

 nitrous oxide and water. 



NH4, NO3 = N.^O + 2 H2O. 



The gas is readily soluble in water, and lias a sweetish odor and taste. 

 When breathed, it at first produces a peculiar exhilarating effect, which 

 is followed by stupor and insensibility. 



This gas has never been demonstrated to exist in the atmosphere. In 

 fact, our methods of analysis are incompetent to detect it, wiien it is 

 present in very minute quantity in a gaseous mixture. Knop is of the 

 opinion that nitrous oxide may occur in the atmosi>here, and has pub- 

 lished an account of exiieriraents {Journal fiir Prakt. Chein., Vol. 59, 

 p. 114) which, according to him, prove tliat it is absorbed by vegetation. 



Until nitrous oxide i< shown to be accessible to plmts, any fuither no- 

 tice of it is unnecessary in a treatise of this kind. 



llydrocliloric Acid C«a<<», IICI, whose properties have been 

 described in How Crops Grow, p. 118, i- found in minute quantity in the 

 air over salt marshes. It doubtless proceeds from the decomposition of 

 the chloride of magnesium of sea-water. Sprengel h:is surmised its ex- 



