Fan. 4, 1883] 
NATURE 
233 
way, of correct determination of free ammonia, viz. the ready 
breaking up of urea (and other amides) when present, on heating 
with sodium carbonate, it woul | be well to ascertain if Schloe- 
sing’s method for determination of ammonia admits of being 
applied to such excessively minute amounts of it as the water 
analyst is concerned with, 
In conduction of the albuminoid-ammonia process proper, 7.¢. 
the distillation with alkaline pe manganate, the author would 
keep the original volume of liquid in the retort constant, by 
admitting ammonia-free distilled water through a capillary tube. 
with a glass stop-cock. When there is so much organic matter 
as to reduce, wholly or greatly, the usual charge of alkaline 
permanganate, he would first determine at about what a rate the 
reagent is used up, then progressively supply its solution, so as 
to keep the original strength as nearly as possible unaltered. 
Permanganate Process—The principle involved in the last 
paragraph applies also to this process. There should be a‘con- 
stat excess of permanganate all through the process. The 
process should be carried on at a pretty nearly fixed temperature 
(say 20° C, if the Tidy method be followed). 
In conclusion, the author expresses a wish that more extended 
biological experiments should be made as to the effects of water 
variously polluted on the lower animals (other animals as well as 
rabbits), and that the action of water introduced into the stomach 
as well as hypodermically injected, should be tested. It would 
be well to have chemical examinations, on uniform plan, from 
time to time made of the water supply of the largest cities at 
periods when the general assent of medical men indicates unusual 
prevalence of, or exemption from, the classes of disease most 
probably capable of origination from the organic pollution of 
drinking-water. The author would especially suggest a com- 
bined chemical and biological inquiry as to the possible effects 
upon living animals of the ferment or ferments of nitrification in 
different stages of that process. Some minor questions con- 
nected with development of nitrites and nitrates from decom- 
posing organic matter also deserve further examination. 
LOCK VER’S DISSOCIATION-THEORY? 
[NX February, 1880, I took occasion, on the ground of my 
observations to the spectrum of chemically pure hydrogen, 
to take objection, to Lockyer’s view, that calcium, at a very high 
temperature, is dissociated.2. From the fact, dfer alia, that of 
the two calcium lines, H’ and H”, only the first is present 
In the spectra of so-called white stars photographed by 
Huggins, Lockyer proceeded to lay down the theory that 
calcium at a high temperature is decomposed into two 
substances, X and Y, of which the first gives the line 
H’, the other the line H”, and that in the stars referred to, 
only the first is met with. Against this I urged that hydrogen, 
besides the four known and easily visible lines, has a remarkable 
line of very intense photographic power, which nearly coin- 
cides with Fraunhofer’s H’, and that one is the more warranted 
in regarding the supposed calcium-line observed by Huggins as 
a fifth hydrogen line, that the hydrogen lines in the spectra of 
those stars are developed in a striking manner, and also the 
ultra-violet star lines observed by Hugeins, agree with the ultra- 
violet hydrogen lines photographically fixed by me. 
Lockyer, however, has not given up his idea of dissociation, 
but sought new proofs of it by the s ectroscopic method. 
He calls attention to the fact, zvfer alia, that in the spectrum 
of sun-spots, certain iron-lines appear broadened, and others 
not ; that, moreover, many of them, as A 4918 and A 4919°7 do 
not occur in the spectrum of protuberances, which show other 
iron lines, but do in the spectrum of spots; that in the latter 
again, the iron lines are occasionally absent, which the former 
contain, and he proceeds to say: ‘‘there is, accordingly, no iron 
in the sun, but only its constituents.” 4 
This argumentation Liveing and Dewar ° have already opposed, 
having proved that certain spectral lines of a substance, ¢.g. 
A 5210 magnesium, and various calcium-lines, are only visible 
when certain foreign matters are present ; in this case hydrogen 
on the one hand, and iron on the other ; that accordingly the 
* A paper by Herr Hermann W. Vogel, read to the Berlin Academy on 
Noveniber 2, 1882, Communicated by the author. 
2 Proc. Roy. Soc., xxviii. 157. 
3 Monatsh. der Berliner Acad. der Wiss., 1880, p. 192. 
4 Comptes Rendus, t. xcii. 904. 
5 Proc. Ray. Soc., 30, 93. Wied. Beibi., iv. 366. 
absence of certain iron lines in the spectra of the spots or protube- 
rances may not be attributed to a dissociation, buat to the absence 
of foreign matters which occasion the appearance of these lines 
in force. 
Lockyer now takes his stand, however, on another fact, which 
is not explained by Liveing and Dewar’s experiments, and which 
certainly seems to afford a firmer basis for his theory of dissocia- 
tion than the facts referred to above. He says: 1 
“The last series of observations relates to the degree of mo- 
tion of vapours in the sun-spots, which it is known, is indicated 
by changesin the refrangibility of lines. If all lines of iron in 
a spot were produced by iron vapour, which moves with a 
velocity of 4o km, in a second, this velocity would be indicated 
bya change of the refrangibility of a// lines. But we find that 
that is z0¢ the case. We find not only different motions, which 
are indicated by different lines, but observe in the degree of 
motion the same inversions as in the breadth of the lines. This 
fact is easily explained, if we suppose dissociation, and Z know 
no more simple way of explaining it.” 
Lockyer cites as an example that in the spots of December 24, 
1880, and January 1 and 6, 1881, a certain number of iron lines 
appeared bent, while others remained straight. 
Now I believe it is possible to explain these facts on the basis 
of numerous observations in spectral analysis of absorption 
without needing to have recourse to the hypothesis of dissocia- 
tion. 
It is known that the position of the absorption-band of a 
substance depends very essentially on the dispersion of the 
medium in which it is dissolved or incorporated. One often 
observes that in strongly dispersive media the absorption-bands 
of a substance are displaced towards the red. Now, the remark- 
able case often here occurs that certain absorption-bands are dis- 
placed with the increase of dispersion of the solvent, while 
others are not. Thus Hagenbach observed that, ¢.g., the chloro- 
phyll bands I. III. and IV. lie more towards red in alcoholic 
than in etheric solution, while the band II. in both solutions 
shows exactly the same position. I observed similar cases with 
uranian protoxide salts? andjwith cobalt compounds.* 
Now Kundt has already called attention to the fact, that for 
absorption-spectra of gases the same rule holds good as for,the 
absorption-spectra of liquid substances. He adds, indeed: ‘‘ It 
is only questionable whether, if, e.g. hyponitrate gas be mixed 
with various other transparent gases, the displacements of the 
absorption-bands are so considerable, that they can be per- 
ceived.” This doubt, however, does not affect the rule sup- 
posed, but merely its experimental verification.® The suppo- 
sition, then, is permissible that, in the same way as with liquids, 
added media also affect the position of absorption-bands in the 
case of gases, and that in this case, as in the other, displace- 
ments of certain bands occur, while the position of others 
remains unaltered. 
When, therefore, in sun-spots, certain irorjlines suffer a dis- 
placement, and others in the same place do not, the cause is not 
motion, but the admixture of a foreign, strongly dispersive gas, 
which acts on the displaced lines and not on the others. It 
follows from this, further, that curvatures of absorption lines of 
the sun-spots need not by any means be always explained as due 
to motion of the absorbing gases in the direction of the line of 
observation, but only where all lines of a matter participate in 
the curvature. 
That bright lines of a luminous gas, also, in like circum- 
stances, ‘‘ by admixture of another non-luminous vapour, or one 
giving a continuous spectrum,” may suffer a displacement, 
Kundt has already shown. 
UNIVERSITY AND EDUCATIONAL 
INTELLIGENCE 
Marcus M. Hartoc, D.Sc., M.A., F.L.S.. has been 
appointed to the Professorship of Natural History at Queen’s 
College, Cork, vacant by the death of Prof. Leith Adams, 
* Herr Vogel quotes a translation in Naturforscher. 
2 Kundt, ¥ubelband Pogg. Ann., p. 620 ‘i 
3 Vogel, “‘ Pract. Spectralanalyse.”’ Nérdlingen bei Beck. P. 248. 
4 Monatsh. der Akad. der Wiss. of May 20, 1878. 
5 Kundt formerly doubted also the possibility of proof of an anomalous 
dispersion in gases and glowing vapours. Recently, however, he has suc- 
ceeded in getting such proof in the case of sodium vapours (Wied, Ann. 10, 
Pp. 321). 
