398. STUDIES ON THE PHENOMENA OF CONTACT. 



the first may be formed in tlie expressed juice after a certain lapse of time. I 

 entertained no doubt, therefore, that this peculiar matter, which cfiects the 

 transformation of oxygen into ozone, is of the nature of fei-meuts. I have 

 verified its presence in all phanerogamous plants whose juice gives a blue color 

 with the resin of guaiacum. It seemed desirable, furthermore, to determine 

 whether the organic acids had anything to do with this color, for some of 

 these acids react, we know, on pectose, starch, sugar, &c., as yeast does. My 

 experiments have, however, satisfied me that the organic acids have no imme- 

 diate action on an alcoholic solution of guaiacum ; that these acids do not pro- 

 duce a blue color in the tincture of guaiacum when alone or when previously 

 mixed with the liquid obtained from mushrooms, the juice of which does not 

 act upon this reagent. On the contrary, certain acids, for example tartaric, 

 citric, and oxalic prevent the coloration of the juice of certain mushrooms, whose 

 juices act on the alcoholic solution of guaiacum when these acids are not present. 

 Although nature then appears sometimes to employ these acids for inducing 

 metamorphoses, it would seem that they do not act in this case. 



From these facts I have come to the conclusion that the peculiar matter 

 spoken of above must be of the nature of a ferment, and the experiments of M. 

 S^hachfc lend support to my opinion ; for that chemist believes that the juice of 

 phanerogamous plants owes its property of turning the resin of guaiacum blue 

 to the presence of what he calls vegetable gelatine, and he affirms that this 

 substance no longer acts when boiled. 



Among my experiments of this kind I will cite one Avhich is easy to repeat. 

 Wc know with what facility a slice of apple changes in the air ; its surface 

 becomes brown in the course of a few minutes. This coloration is known to be 

 owing to the action of oxygen ; it is a commencement of eremacausis. 



Now I think I have proved, as will be seen in the sequel, that when oxygen 

 acts thus on organic bodies, producing the phenomenon known by the name of 

 eremacausis or slow combustion, this oxygen is always in the state of ozone at 

 the moment when it reacts.- To verify this with the slice of apple, we need only 

 diffuse over the fruit a drop or two of the tincture of guaiacum ; at the end of 

 three or four seconds the reagent changes to a bright blue color. Let it be ob- 

 served that this tincture, exposed to the air on glass, porcelain, clean paper, 

 &c., will not change color for a long time; and, moreover, as has been already 

 seen, the organic acids are iiiactive in this phenomenon. 



I have carried my experiments further, and have arrived at the conclusion 

 that the first phase of a\\ fermentation or eremacausis hjj the ivfiuencc of the air 

 consists in the transformation of the oxygen of the air into ozone. Thus, as in 

 the most ordinary cases of inorganic mineral chemistry, all commences with a 

 phenomenon of polarity. 



What has just been said is particularly striking, as regards the phenomena 

 presented by the resinijication or oxidation of certain essential oils. The extra- 

 ordinary manner in which the oil of turpentine (tcrebenthine) exalts the activity 

 of oxygen is now known to all chemists. The aerated turpentine transforms 

 sulphurous acid' into sulphuric acid, the oxide of lead into peroxide, arsen- 

 ious into arsenic acid, &c. — (KuMmann.) Other essences act in the same 

 manner on oxygen by transforming it into ozone ; and in my experiments 

 I have never yet met with an essential oil which did not exercise this property. 



Still further, in examining different fats and fixed oils, I have been convinced 

 that they possess, in a certain degree, as regards oxygen, the same properties 

 with the essence of turpentine and the volatile oils. 



The substances with which I have most frequently experimented arc crude 

 turpentine, the extract of bitter almo*nds, of cinnamon, of caraway, the balsam 

 of Peru, most of which were acid and reacted on litmus paper. They produced, 

 however, no effect on the ozonoscopic paper until an absorption of oxygen 

 had taken place. 



