20 CHEMICAL AGENTS AND PROTOPLASM [Ch. I 



or by acting on the aldehydes, 



;c = + H^s = ;c = s + h^o. 



It acts rather energetically upon algse and Infusoria. In Ver- 

 tebrates, the central nervous system is attacked and the oxy- 

 hemoglobin of the blood is altered. 



Sulphurous oxide (SOj) attacks members of the aldehyde 



^^"'^P'- E\ E\ /SO3K 



■)G = -f SO3KH = )C— OH 

 H/ h/ \h 



aldehyde. 



0.1% kills lower fungi in a few minutes, 0.01% in a few hours. 



Selenous oxide (SeOj), which acts chemically much like SO^ 

 and has a much greater molecular weight (64 : 111), acts less 

 energetically as a poison. A 0.1% solution kills Spirogyra 

 and Zygnema in 3 hours, while 0.01% is scarcely injurious. 

 Tellurous oxide (TeOg, mol. wt. = 157) is non-poisonous, 

 although chemically closely allied to the two preceding. 

 (BOKORNY, '93.) 



Aldehydes. — The poisonous action of these substances de- 

 rived from oxidation of alcohol is dependent upon their insta- 

 bility. So we find that an aldehyde, which, like grape sugar, 

 is fairly stable, is likewise non-poisonous ; while formaldehyde, 

 which is very unstable and active, is correspondingly poisonous. 

 Aldehydes attack especially the unstable amides, affording ni- 

 trogenous compounds ; e.g. — 



CK, ■ NH2 + CH2O = CeH^NCH^ + H,0. 



Now, even in passive albumens, part of the N is in the form 

 of amido-groups ; for, in treating with nitric acid, much nitro- 

 gen is set free, which would not occur were all of the N second- 

 arily or tertiarily bound up. (LoEW, '93, p. 58.) Hence the 

 poisonousness of aldehydes for living albumens. 



Formaldehyde. — This substance (H — CH : O) acts upon 

 propep tones and upon albumen, affording compounds which are 

 not readily soluble. An aqueous solution of — 



