Sepé. 29, 1870] 
NATIURE 
441 
the Exeter meeting, when it was in operation at only two works. 
It is now either in operation or on the point of being adopted at 
almost all the works in this country, and at a number of works 
in France and Germany. In consideration of the fact that the 
production of chlorine will probably be completely revolutionised 
by the Weldon process, and considering, likewise, that chlorine 
is largely prepared in the neighbourhood of Liverpool and in 
_ other parts of Lancashire, the author had agreed to the request 
of Prof. Roscoe that he should submit to the section a brief 
account of the practical results, which the process had been found 
to yield under more extended experience, and of the develop- 
ment which it had undergone during the year. The author first 
described the apparatus employed, and exhibited a small model 
of it, and then proceeded to state that the chloride of manganese, 
which results in the ordinary preparation of chlorine, and which 
is generally acid, is neutralised by adding to the liquor finely- 
divided carbonate of lime. The liquor then consistsof a neutral 
mixed solution of chloride of manganese and chioride of calcium, 
and contains, in suspension, a large quantity of sulphate of 
lime and smaller quantities of oxide of iron and alumina. The 
clear solution, after settling, is oxidised by passing into it a blast 
of atmospheric air froma blowing engine, and heated, if neces- 
sary, by a current of steam. Milk of lime is then run into the 
oxidiser until the liquid ceases to give a manganese reaction with 
solution of bleaching powder. A further quantity of milk of 
lime is added, and ultimately from eighty to eighty-five per cent. 
of the manganese is converted into peroxide. The mixture is 
allowed to settle, the chloride of calcium solution forming the 
supernatant liquid is run off, and the residual black mud con- 
taining the manganese peroxide is used in the stills where hydro- 
chloric acid is decomposed and chlorine gas produced, A resi- 
dual liquor such as was commenced with, results, and the round 
of operations is begun again; and so on, time after time indefi- 
nitely. After giving an outline of his mode of treating still 
liquor, Mr. Weldon described at considerable length the details 
of the process, both as to quantities of materials employed and 
obtained, and the nature of the chemical compounds formed at 
_ different stages of the process. As explained by Prof. Roscoe, 
_ the principle upon which the process depends is that, although 
when alone, the lower oxides of manganese cannot be oxidised 
by air and steam under the ordinary pressure to the state of 
dioxide, yet this is possible when one molecule of lime is pre- 
sent to each molecule of oxide of manganese. The manganous 
| oxide is precipitated from the still liquors with the above excess 
3 
; 
—— 
of lime, and by the action of steam and air on this, a black 
powder, consisting of manganese dioxide and lime, or calcium 
manganite (MnO, Ca O), is formed. This compound is again 
capable of generating chlorine from hydrochloric acid, and thus 
} the chlorine process is made continuous with a working loss of 
_ only 23 per cent. of manganese. 
_ Ashort discussion followed the reading of the paper, in the 
course of which Mr. Gossage stated that his experiments on the 
improvement of the chlorine process had extended over thirty- 
five years, and he was glad Mr. Weldon’s efforts had been 
_ attended with such a large'measure of success. 
a 
4 
Air Pollution from Chemical Works. — Mr. Alfred E. 
_ Fletcher, F.C.S., one of the inspectors under the Alkali Act. 
The author remarked that during the progress of many manu- 
facturing processes gases or vapours were given off, which pass- 
ing into the surrounding air, polluted it and rendered it more or 
less unfit for animal or vegetable life. If all noxious vapours 
were to be suppressed by the summary stoppage of the manu- 
facturing processes causing them, we must dispense with the 
use of a variety of useful substances ; indeed, it might be said 
that every manufacture was accompanied at its birth by some 
offensive smell or smoke. Still, the public were right in requir- 
ing that noxious vapours should be reduced to a minimum. 
Those who were not acquainted with manufactures would be 
surprised at the large amount of noxious vapours discharged 
- from works. He then referred to the direction which he thought 
- future legislation should take, his opinion being, he said, guided 
by the observations of Dr. Angus Smith, in his reports as chief 
inspector under the Alkali Act. In places where complaints were 
- made against manufacturers by farmers, as to damage to their 
crops by corrosive smoke, let the district be called ‘fa manu- 
facturing district,” upon the requisition of a certain number of 
inhabitants. To such district an inspector should then be 
appointed, who should have power at any time to ascertain the 
- nature and amount of gases escaping from the various works. 
- Atthe end of each month, or a longer period, the inspector 
should publish a list of all the works in his district, with a num- 
ber indicating the average amount of acid vapour he had found 
upon his visits. There the inspector’s duties should terminate, 
as he should be neither prosecutor nor judge, but merely pub- 
lish the facts ascertained, which the farmer himself could never 
have gathered. He contended that such a plan would be bene- 
ficial in its operation. It would be universal in its application, 
and would embrace every description of manufacturing works. 
Hitherto legislation had been partial. There was an Alkali Act, 
but it regulated the alkali manufacture only. 
In the discussion it was strongly urged that over-legislation 
on this question should be avoided, and that the crops do not 
suffer to the extent which was sometimes imagined. The Alkali 
Act had been so far beneficial as to call the attention of manu- 
facturers to the subject of air pollution, and they had been in- 
duced to employ improved apparatus at their works. 
On the Phenomena of the Crystallisation of a Double Salt.— 
Mr. J. Berger Spence. Mr. Spence said that hitherto many 
scientific chemists had doubted the possibility of producing soda 
alum ; but the results of upwards of fifty experiments which he 
had made conclusively showed that this salt can be produced 
under certain circumstances. The principal point of interest 
in Mr, Spence’s paper consisted in the discovery, made by 
him, that the crystals are produced from an amorphous mass, 
which is formed when the solution is prepared at high densities. 
The immediate result of this discovery may be that the large 
quantity of ammonia which is now used in the production of 
alum will be displaced in favour of soda, and that the valuable 
fertiliser, ammonia, which has no intrinsic value in alum, will be 
given to the soil, which, in an economic point of view, will be 
of considerable advantage to the country. 
SECTION C,—GEOLOGY 
Report on British Fossil Corals.—Prof. P. M. Duncan. The 
distinction between the paleeozoic and later coral faunas was 
shown to be not so exact as was supposed, and that the aporose 
and perforate corals existed in the palzeozoic rocks, as well as 
rugose and tabulate forms, which latter had closely allied recent 
analogues. The report contained a new classification of the 
Tabulata, and entered into the Alcyonarian characters of the 
Chetetine and the Hydrozoan characteristics of the AZeforide. 
On the Fossil Elephants from Malta.—Dr. Leith Adams, 
After referring to his former reports, communicated to the Asso- 
ciation in 1865 and 1865, in which the situation and nature of the 
Maltese ossiferous caves were described, Dr. Leith Adams now 
submitted further observations on the elephantine remains which 
has been collected by him in enormous quantities in those locali- 
ties, and pointed out the important results that might be expected 
to flow from the comparison of these materials with those which 
had been brought by Captain Spratt from Zebbug, in which the 
late Dr. Falconer, in the yesr 1862, had discerned the existence 
of a dwarf or pigmy species, together with that of a larger form. 
Subsequently, Mr. Busk, on proceeding to work out Captain 
Spratt’s collection in detail, found reason to discriminate three 
distinct forms, one of the average dimensions of the existing 
African and Asiatic species, and two others, differing from each 
other not only in size, but, as it would appear, in other osteo- 
logical characters, but both of comparatively small or dwarf 
stature. The Zebbug collection, however, afforded but very 
scanty evidence with respect to the largest form, whilst that made 
by Dr. Leith Adams abounds with its renmains, and will conse- 
quently allow of the correct determination of the true relaticns of 
that form withthe two smaller forms found in association with it, 
as well as with other existing and extinct species, and especially 
with £. aztiguaus, whose relations up to the present time have 
remained obscure. Mr. Busk, by whom the paper was commu- 
nicated, exhibited specimens selected from Dr. Adams’ collection, 
proving the existence of the three forms above adverted to. 
Report on the Exploration of Kent's Cavern.—Mr. W. Pengelly. 
During the past year the committee had investigated the only 
portions of the eastern division of the cave which had remained 
unexplored. Those portions had been called by the Rev. J. 
McEnery, the North and South Sally Ports in the belief that they 
led to external openings. The South Sally Port has a south- 
eist direction into the hill, and away from the hill-side ; it occu- 
pies a space of 80 feet by 4o feet. It was filled with, first, a red 
cave-earth from 12 to 20 inches thick ; second, a stalagmitic 
floor from 1 to 24 inches thick ;*and third, a caye-earth ef un- 
known depth, but exceeding 5 feet. The diggings yielded a 
