110 
NADRORE 
| NovEMBER 29, 1906 
of hundredweights of indigo produced was never less than 
112,000, and in 1894-5 reached 238,000. During 1905-6, 
on the contrary, the number of acres under cultivation 
fell to 381,000, and the amount of indigo produced to 
45,000 cwt. The case of cotton, however, is quite of a 
different character. The number of acres under cultivation 
has steadily increased in recent years. In 1899-1900 about 
12,000,000 .acres- were planted, but during 1905-6 the 
number was well on the way to 21,000,000. The out- 
turn in bales of goo Ib. increased in a similar manner 
from 1,090,000 in 1899-1900 to 3,250,000 in 1905-6. The 
volumes certainly provide a rich storehouse of material 
for readers interested in Indian affairs. 
SEVERAL important papers appear in the October 
number of the Journal of Hygiene (vi., No. 5). 
Dr. Ashburton Thompson, President of the Board of 
Health, New South Wales, discusses the epidemiology 
of plague, particularly the part played by the rat 
and flea in its transmission; Prof. Nuttall and Dr. 
Graham Smith contribute an important and exhaustive 
account of canine piroplasmosis and of the morphology 
and development of the parasite Piroplasma canis; Mr. 
A. T. MacConkey describes the bacteriology of some cases 
of food poisoning which have come under his notice; and 
Mr. J. D. Thomson certain blood parasites of the mole. 
An interesting instance of spirochzetosis in mice is de- 
scribed by Mr. C. M. Wenyon, and Dr. Andrew Balfour 
gives some notes on herpetomonas parasites in fleas. 
Finally, the report of the commission for the suppression 
of ankylostomiasis in Porto Rico is abstracted. The 
disease is very prevalent, and probably 90 per cent. of the 
inhabitants, who number about one million, suffer from 
it, and are more or less incapacitated. It is estimated 
that for an expenditure of 20,000]. per annum 
persons could be treated a year. 
100,000 
In the last volume of the Proceedings of the Institution 
of Civil Engineers (vol. clxv., session 1905-6, part iii.) an 
account is given by Mr. Baldwin-Wiseman of a series of 
investigations made by him during the last three years as 
to the relationship between the porosity of rocks, and 
the flow of water through the interstices, under varying 
pressures. A description and illustration of the apparatus 
employed also accompanies the paper. The stones selected 
for experiment range from the Carboniferous to the Cre- 
taceous rocks. The stones were carefully selected and 
dressed into the form of cylinders 13 inches long and 
6 inches in diameter. These blocks were placed in a steel 
case, and precautions taken to prevent any leakage. The 
- water was supplied from an hydraulic accumulator at vary- 
ing pressures up to 75 lb. on the square inch. A drop of 
the piston, which acted in the steel case, of 1 centimetre 
was equivalent to a discharge of 62:06 cubic centimetres, 
and the area exposed was such that a discharge of 1° cubic 
centimetre per second was equivalent to one gallon per 
hour per square foot of surface. Special attention was 
given to the question of re-soakage as bearing on the rate 
and amount of recharging depleted strata after a long- 
continued drought. The results of the investigations are 
given in thirteen tables in the appendix to the paper; where 
also there are two tables showing the geological formation, 
depth of wells, quantity of water pumped, and other par- 
ticulars of a large number of waterworks, with details of 
‘the filter-beds. 
Tue report of the Canadian Government Commission 
_ appointed to investigate the zinc resources of British 
Columbia and the conditions affecting their exploitation 
NO. 1935, VOL, 75] 
| has been published by the Mines Department of the De- 
partment of the Interior (Ottawa, 1906). It forms a hand- 
some volume of 400 pages, with numerous maps and 
illustrations. In British Columbia the silver-lead ores 
occur in close association with zine ore, which hitherto 
has proved a detriment to the value of the former. The 
commission was appointed to arrive at a knowledge of the 
economic value of the zinc ores. Mr. W. R. Ingalls, an 
authority on zinc from the United States, was appointed 
to draw up the report, and Mr. Philip Argall, of Denver, 
Colorado, and Mr. A. C. Gardé, of Nelson, British 
Columbia, to act as his assistants. Their report contains 
a vast amount of authoritative information on the mining 
and milling of zinc ores. Some of the undeveloped zine 
deposits of British Columbia are reported upon by Dr. 
A. E. Barlow, of the Dominion Geological Survey. The 
possibility of enriching the zinc ores of British Columbia 
to a high degree by magnetic separation is thoroughly 
demonstrated by the tests conducted by the commission. 
In every case it has been possible to produce a zine con- 
centrate assaying upwards of 4o per cent. of zinc, and in 
some cases as much as 57 per cent. of zinc. Magnetic 
separators should be of the high-intensity type, and means 
for roasting the ore are required. The Blake electrostatic 
separator proved unserviceable for these ores, which 
appear, however, to be amenable to separation by flotation 
processes. Electric smelting of the zinc ores is not advo- 
cated, as this process must undoubtedly go through many 
stages of experiment before it can be pronounced a metal- 
lurgical and commercial success. Smelting with Canadian 
coal is, however, quite feasible commercially. Zinc ores 
are widely distributed, and the situation is excellent for 
the creation of a zinc industry in British Columbia. 
AN interesting contribution to the study of pseudo-solu- 
tion, dealing in particular with the colloidal forms of ferric 
hydroxide, is made by F. Giolitti in two papers published in 
the Gazzetta (vol. xxxvi., ii., pp. 157 and 433). When ferric 
hydroxide, freshly precipitated by ammonia and thoroughly 
washed with water, is examined microscopically, it appears 
to consist of homogeneous gelatinous masses. After being 
left in contact with water during several months, minute 
“nuclei ’’ form in the gelatinous particles, and on adding 
acetic acid the gelatinous portion dissolves, leaving behind 
the ‘‘ nuclei’’ in the form of minute spheres of a nearly 
uniform diameter of about 7 mw. These nuclei, after 
being allowed to settle, form with pure water pseudo- 
solutions which are characterised by being coagulable by 
dilute nitric acid. A definite concentration of nitric acid 
necessary to produce coagulation corresponds to each con- 
centration of the colloidal solution. The pseudo-solutions 
of ferric hydroxide prepared by different methods have 
different physical and chemical properties; different solu- 
tions of the same concentration have, for instance, different 
absorption spectra. With some solutions the addition of 
nitric acid causes the hydroxide to dissolve as nitrate, whilst 
with others a coagulation of the ‘‘ hydrosol *’ is obtained. 
With precipitated tungstic acid very remarkable phenomena 
are observed. On washing the freshly prepared material 
very thoroughly with water, suspensions are obtained 
which, after being left during several days, separate into a 
number of well-defined strata, differing in colour and degree 
of opalescence. From these different strata pseudo-solu- 
tions can be prepared which at the same concentration have 
different limits of stability in presence of a coagulating 
agent such as nitric acid. The explanation given of these 
phenomena is that the different pseudo-solutions contain 
particles of different magnitude or molecular complexes 
