CHEMISTRY. 



91 



converging upon the positive pole, or simply causing 

 the latter to be covered with a faint glow. A cur- 

 rent of air or oxygen sent into the tube must pass 

 through this, and ozone is very rapidly produced, 

 and in great quantity. The condensers are of course 

 not used with the machine when this apparatus is 

 employed. 



M. Widemann, a distiller, of Boston, claims 

 to apply ozone for the removal of fusel-oil 

 from whiskey the volatile oil disappearing, 

 after contact with ozone, in about twenty min- 

 utes, fie writes to the Mechanics' Magazine that 

 during the past year he was applying this pro- 

 cess (undescribed) to 300 barrels of whiskey of 

 40 gallons each, daily. Adding water to Indian- 

 corn whiskey, and subjecting it to the same 

 process, he transforms it into vinegar, for 

 pickling purposes, and at a factory in White 

 Plains, K Y., was making 90 barrels, of 40 

 gallons each, of this vinegar, per day. 



Fluorescence. In a series of papers contrib- 

 uted to Poggendorff^s Annalen, Hagenbach 

 has given his extensive researches on this sub- 

 ject. The following are his main conclusions : 

 All the rays of the spectrum are capable of ex- 

 citing fluorescence. As to the extent of fluo- 

 rescence in the spectrum, there are cases (as 

 that of fluor-spar) in which it only begins in 

 the violet after G; and others (as chlorophyl) 

 in which it is spread over the entire spec- 

 trum. No fluorescent substance was met with 

 which did not fluoresce in the neighborhood 

 of the line H. It was proved that, where rays 

 excite fluorescence, a corresponding absorption 

 takes place; also that the rays called forth 

 are never more refrangible than the exciting 

 rays. These proportions were first laid down 

 by Stokes. The question whether fluorescence 

 in the solid state implies fluorescence in a state 

 of solution, and vice versa,, must be answered 

 differently for different substances. Some 

 substances fluoresce in the solid state, and not 

 at all in solution; some greatly in the one 

 state, little in the other; some show strong 

 fluorescence in both states; some fluoresce 

 little in the solid state, and greatly in solution; 

 some fluoresce only in solution. Herr Hagen- 

 bach considers it probable that phosphores- 

 cence and fluorescence are phenomena differ- 

 ing in degree only, not in kind ; though fur- 

 ther data are necessary to the elucidation of 

 this. He finds much similarity between the 

 fluorescence spectra and many of the spectra 

 of phosphorescent substances. 



^ Atoms and Molecules. Dr. _S. D. Tillman 

 discusses in the American Chemist the much- 

 vexed question of the indivisibility of atoms, 

 and makes out an apparently strong case for the 

 atomic theory. Conceding, however, that at- 

 oms are indivisible and indestructible in the 

 present order of things, he does not regard 

 that fact as precluding the supposition that 

 the atom maj be a cluster of smaller particles 

 held together by a powerful affinity, which, 

 when counteracted, would leave them free to 

 move within a given sphere, and he suggests 

 that the relative position of such particles may 



modify the combining capacity of the atom. 

 Moreover, the normal position of such parti- 

 cles may determine not only the peculiarities 

 of elemental spectra, but produce other effects 

 not dependent on the amplitude of atomic os- 

 cillations, thus favoring the inference that the 

 atom itself is a receptacle of force. Dr. Till- 

 man thus summarizes the present evidence in 

 support of the atomic theory : 



1. Atomic Weights. Elements combine in ex- 

 tremely minute parts, according to the law of defi- 

 nite and multiple proportions. The atomic weight 

 of an element is either its equivalent weight, or a 

 multiple of it ; as such multiple cannot be divided by 

 reactions, its weight must conform with the atomic 

 number. Whatever changes of position the combin- 

 ing weight of an element may undergo in a series of 

 molecular metamorphoses, that is to say, however 

 many times it may be displaced and replaced in 

 chemical combinations, it invariably retains its char- 

 acteristic weight. This invariability of weight is an 

 essential property of the atom. 



2. Atomic Volume. Gases unite in equal volumes 

 or multiple volumes. If hydrogen be taken as unity, 

 the density of each elementary gas is identical with 

 the weight of its atom. The atomic volume, deter- 

 mined by dividing the atomic weight of a body by 

 its specific gravity, has been the means of revealing 

 many interesting iclations among compounds of simi- 

 lar structure, and among many containing different 

 components and of unlike structure. 



3. Atomic Heat. It has been shown by experi- 

 ment that quantities of each element conforming 

 with its atomic number have the same capacity for 

 heat, excepting only carbon, boron, and silicon ; 

 these, it is believed, will yet be found to conform to 

 the law that the specific heats of all atoms are the 

 same. This law is regarded as a direct confirmation 

 of atomic weight. 



4. Molecules. According to the atomic theory, 

 chemical forces are brought in equilibrium when at- 

 oms combine and form a molecule. Every gas and 

 every vapor undecomposed has a density proportional 

 to its molecular weight. All known molecular com- 

 binations and combining proportions are in accord- 

 ance with the atomic doctrine. Decomposition by 

 electrolysis affords some evidence that the constitu- 

 ent parts of a molecule which are simultaneously 

 separated are proportionate to atomic weights. 



5. Atomic Combining Capacity. The modern doc- 

 trine of types and suDstitutions is solely based on 

 the individuality of the atom, without which the 

 whole fabric of typical structures must fall. 



6. Isomerism. The fact that bodies containing the 

 same elements, and in precisely the same propor- 

 tions, exhibit different properties, has been thus far 

 accounted for, only on the supposition that atoms are 

 differently arranged in each body. These differences 

 in arrangement depend not only on the relative po- 

 sition of atoms, but also on the order as to time in 

 which they combine ; for two or more atoms having 

 such precedence over others as to combine first may, 

 by that means, form a radical of such permanence as 

 to play the part of an atom. Aside from the ques- 

 tion of radicals, we may ascertain the number of dif- 

 ferent bodies which can be formed from the same 

 number of different atoms by an application of the 

 mathematical law of permutations. 



7. Homogeneity. The uniformity of structure and 

 appearance of any element or chemical combina- 

 tion of elements furnishes the most palpable proof 

 of the identity in size and shape of those definite 

 parts which we designate as molecules. This homo- 

 geneity is retained under different degrees of press- 

 ure, thus making it apparent that molecules are not 

 only identical in structure, but that they approach 

 and recede in precisely the same manner under the 

 same conditions. 



