STUDIES ON THE PHENOMENA OF CONTACT. 397 



pretatiou. Ordinary hydrogen, disengaged from water by zinc and sulphuric 

 acid, exerts no action on a solution of sulphate of silver ; the hydrogen disen- 

 gaged from water by the pile decomposes that salt. 



Electric action is peculiarly effective in augmenting or diminishing the 

 polarity of a body. Thus oxygen may be converted to the state of ozone by 

 the electric spark. Let a piece of copper and one of tin be placed in two 

 capsules of porcelain, and an acid be poured on the two metals ; they will be 

 attacked very nearly in an equal degree. But if the tin be placed in the same 

 capsule, and in contact with the copper, and the acid be then added, the tin alone 

 will be attacked, and more actively than in the first case, because its polarity on 

 account of its contact with the copper has become greater than that of this 

 metal, and the acid will not act on the copper until all the tin has been dissolved. 



We particularly desire our readers to bear this experiment in mind, for 

 what we shall adduce in the sequel for the purpose of demonstrating what 

 passes in catalytic reactions will bo, in effect, but little else than modifications 

 of that which has just been cited.. 



When the polarity of a body is strongly modified, such body is styled 

 "allotropic," (from aXkorpoTtog, of different nature.) Thus ozone is allotropic 

 oxygen ; the chlorine of Andrews is allotropic chlorine ; the hydrogen produced 

 by the pile, and which decomposes sulphate of silver, is allotropic hydrogen, &c. 



But this allotrojjic state of bodies is but slightly permanent, as will be here- 

 after seen ; and, further, we shall endeavor to prove that bodies assume this 

 state at the moment when they enter into combination. In regard to this I 

 shall first cite my own experiments and observations on oxygen. M. Schcinbein 

 having expressed an opinion that the action of oxygen on certain organic bodies, 

 such as venous blood, &c., depends on the presence of a substance capable 

 of transforming oxygen into ozone, I was led to study this allotropic modifi- 

 cation of oxygen under the same point of view. 



First, I repeated and confirmed the ingenious experiments of the learned 

 chemist of Basle, in which he studied the action of ozone in the mushroom ; 

 and these studies appear to me to cast light on the subject with which we 

 are occupied It is known that the flesh of certain species of the mushroom and 

 boletus (among others the Boletiis luridus, B. cyanescemis, &c.) possesses the 

 remarkable property of changing color when broken and exposed to the atmos- 

 phere. For instance, the internal tissue of the boletus luridus becomes blue under 

 these. circumstances. Now, experiment shows us that this boletus contains a 

 colorless, resinous principle, soluble in alcohol, and this alcoholic solution is 

 affected, as regards oxygen and ozone, in the same way with the alcoholic 

 solution of the resin of guaiacum, which has been employed by M. Schonbein 

 and myself in some experiments as a test for ozone. This resinous prin- 

 ciple, Avhich is separated from the boletus by means of alcohol, can assume no 

 color spontaneously from the air when it is separated from the mushroom ; but 

 in the parenchyma of the vegetable it promptly becomes blue on the least con- 

 tact with oxygen. Experiment further proves that the expressed juice of 

 several mushrooms contains an organic principle possessing the property of 

 transforming oxygen into ozone, so that, by causing a current of air to pass 

 through this juice, a certain quantity of oxygen is retained in the liquid in the 

 state of ozone, the presence of which is indicated by mixing with the liquid a 

 little of the alcoholic solution of guaiacum, or that of the colorless resin of the 

 boletus. If the liquid contains no ozone, no coloration occurs; if ozone be 

 present, a deep blue tint is obtained. 



I have repeated experiments of this kind upon a great number of different 

 mushrooms, and on the juice of different phanerogamous plants. I have found 

 that the peculiar matter which transforms oxygen into ozone may exist in 

 mushrooms, where the colorless resin of the boletus tribe does not occur ; the 

 peculiar matter and the resin may be wanting in certain other mushrooms, but 



