70 [March, 1902.] 
IMPERIAL INSTITUTE JOURNAL. 
causing the material to ooze out, and as it drops it is collected on the plantain leaves with 
which the floor of the room is covered. 
The masses of soft resin adhering to the plantain leaves are once more heated, and a 
piece of aloe leaf attached to one end, whereby the operator can stretch the soft resin in all 
directions, forming ultimately a large sheet of uniform thickness. 
In the better class of factories the plantain leaf has been abandoned in favour of polished 
tiles, and tire stretching is done by attaching the warm masses of lac to hot zinc rollers, but 
the final stretching is still accomplished in the old-fashioned way. Finally the sheets are 
carefully inspected, and all dark coloured or dirt-impregnated pieces broken out. 
As regards the chemistry of shellac, practically nothing is at present known, and the 
Agricultural Ledger article merely gives a summary of the results obtained by John, 
Unverdorben, and Tschirch and Farner. Of these, the work of the two first-mentioned 
chemists was accomplished many years ago, before methods of attacking such difficult 
problems as the constitution of resins had been evolved, whilst the investigation conducted 
by Tschirch and Farner was of a very superficial character, as the following summary shows. 
T hese authors found that the specimen of shellac with which they worked contained 74 per 
cent, of true resinous matter and small quantities of lac dye, moisture, and inorganic impuri- 
ties. The resin consisted of two distinct substanses, one soluble in ether and the other 
insoluble. To the former they assigned the constitution of an ester of a resino-tannol and 
aleuritic acid, whilst they regarded the second as an indifferent substance, and named it 
erythrolaccin, since it formed yellow spangles which, on heating, sublimed and condensed to red 
needles. Aleuritic acid was regarded as a paraffinoid acid, and therefore the authors assumed 
that shellac and amber differed from all other resins in this respect, an assumption scarcely 
warranted by our meagre knowledge of the constitutions of the resin acids. 
A series of analyses of seed-lac from Assam is published by Mr. Hooper, showing that the 
amount of resin contained in this material varies according to the care which has been exercised 
in grinding and sifting it, the finest powder containing the highest percentage of resin. The 
bleaching of shellac by chlorine, sulphur dioxide, carbon, and other agents is also described, 
and outlines of the processes suggested by various manufacturers ara given; but no explana- 
tion is offered of the fact that much of the bleached shellac of commerce is usually insoluble in 
alcohol, and therefore useless for varnish making. 
The shellac of commerce usually contains a small amount of the wax, simultaneously 
produced by the insect. This substance was investigated by Benedikt and Ulzer in 18S8, and 
shown to consist essentially of the palmitic and stearic esters of myricyl and ceryl alcohols, 
and is therefore somewhat like beeswax in composition, but so far it has not been used for 
similar purposes ; Hooper suggests that its hardness and stability render it an excellent 
material for seals to be attached to documents. 
The Industrial and Art Uses of Lac. 
The native artisan employs this resin for a bewildering variety of purposes, but especially 
for the ornamentation of wood and metal work, to which it is applied either in the form of 
a varnish or melted. In the latter case the skilled worker, by employing lac coloured by 
aniline dyes or inorganic pigments, is able to produce complicated and artistic designs with 
very primitive apparatus. The original article gives an interesting account of the various 
ways in which this lac decoration is accomplished, but an adequate summary would occupy 
much space, and, moreover, would only interest specialists in wood work, so that it may for 
the present purpose be omitted. In addition to this, the most general outlet for the resin in 
India, it is used as a bed for hammering out gold and silver by native smiths, while lapi- 
daries employ it for the embedding material of their grindstones. Cheap ornaments and toys 
are made from it, either entirely or with a thin external coating of more valuable material. 
Lac dye is still employed to a small extent by native tanners and wood-stainers, whilst Hindoo 
ladies often use it to stain the soles of the feet and palms of the hand. In Europe and 
America the resin, in the form of shellac, is one of the mosL common ingredients of the spirit 
varnishes and polishes used in cabinet-making and the manufacture of hats, whilst concen- 
trated solutions in methylated spirit are often employed as cements. The following statistics 
compiled from the official returns show the extent of India’s export trade in this 
material : — 
Shellac. 
Lac-dye. 
Year. 
Total Export. 
Value. 
To United 
Kingdom. 
To United 
States. 
To 
Continental 
Ports, 
Total 
Export. 
1876-1877 . 
1S84-18S5 . 
1S97-1S9S . 
1899-1900 . 
Cwt. 
89,880 
106,747 
189,329 
195,239 
Rupees. 
42,20,497 
45 , 36,326 
92,86,795 
92,65,600 
Cwt. 
68,654 
82,291 
60,257 
Cwt. 
21,152 
53 , 6 9 8 
79 , 6 iS 
Cwt, 
15,413 
51,069 
52,102 
Cwt. 
19,051 
106 
Nil. 
1 
These figures are of particular interest, as showing the remarkable decline in the export 
of lac dye which followed the introduction of synthetic dyes, and as illustrating the fluctua- 
tions in the price of shellac. A third curious feature is the falling off in the export to 
the United Kingdom, which is explained by the corresponding increase in the shipments 
to continental ports, since continental importers now generally buy direct from Calcutta 
instead of via London, as was formerly their custom. 
SOFT PORK. 
Canada, during the year 1900, exported bacon to England of the value of $12,000,000. 
Among the qualities necessary for first-class bacon in England none is of greater importance 
than firmness, any tendency to softness or tenderness being quite sufficient to rate it at second- 
class prices, and, if this softness is at all pronounced, to make it unsaleable at a profit. These 
facts have led the Canadian agricultural authorities to make an investigation into the character 
and causes of soft pork, this detrimental character having been especially developed in the 
produce of certain districts. Five series of experiments were made, during 1S99 and 1900 
respectively, at the central experimental farm, Ottawa, consisting of feeding trials, followed 
by a chemical examination of the pork produced. 
The first step was to ascertain the difference in composition of firm and soft pork, so 
that chemical analysis might be employed as discriminating agent of the quality. Samples of 
the two qualities were taken, and the olein determined in the dry filtered fat, when the 
following results were obtained : — 
Firm. 
Soft. 
Loin. 
Shoulder. 
Loin. 
Shoulder, 
Olein (calculated) ...... 
Palmitin and Stearin ..... 
Ratio of Palmatin and Stearin to Olein . 
% 
6371 
26’29 
UI76 
% 
64 ‘40 
35 ' 6 o 
I : 1 ‘8o 
<t 
79'95 
20 '05 
i : 3*99 
% 
SonS 
19-82 
1 : 4’02 
Vol. VIII. No. 87. 
These figures show very clearly that the fat of soft-bacon contains a much smaller propor- 
tion of solid fats, palmitin and stearin, which explains its characteristic flabbiness. The fat 
of immature pork was found to contain more than the average amount of olein, and was 
consequently more or less soft. The fat of bacon classed by porkers as very firm contains 68 
per cent, of olein or less, while very soft contained 75 per cent, or more. 
In the first series of experiments the influence of the character and quantity of food given 
to the animal, its age when slaughtered, of exercise and locality, upon the development of fat 
were determined. In the second series it was considered unnecessary to repeat the details as 
regard eastern and western origin, limited and unlimited ration, and exercise, as these factors 
exerted very little influence on the firmness of the resulting pork, and only the effect of 
varying ration was determined. A summary of the results is given in the following table, 
beginning with the firmest pork. The figures relate to the fat derived from pigs fed on the 
given rations : — 
Composition of Ration. 
Olein. 
Melting 
Point, 
i corn meal ; \ oats, pease, barley (J each), and skim milk ; sugar 
beets 
% 
66 '9 
32*3 c. 
Pease 
67-2 
32-5 
i corn meal; oats, pease, barley (-g- each) ; skim milk and mangels 
Oats, pease, and barley (£ each) 
68*2 
327 
6S7 
32 A 
^corn meal ; oats, pease, barley {■§• each) and skim milk ; turnips 
Corn meal and skim milk 
70*4 
3 2 ‘3 
70 ’9 
33*3 
i corn meal ; } oats, pease, barley Q each), and skim milk 
i corn meal ; 3 oats, pease, barley (j each), and cooked pumpkins . 
72-3 
31-1 
733 
31*4 
3 corn meal ; J oats, pease, barley and artichokes .... 
73 ’4 
3 i ’5 
1st period, oats, pease, barley (-J- each) ; 2nd, period corn meal . 
73‘9 
31-1 
3 corn meal ; oats, pease, barley ( J each) . . ■ . 
74-6 
30 *3 
1st period, corn meal ; 2nd period, oats, pease, barley (J each) . 
76*1 
3 ° *9 
Corn meal only 
83-6 
28-6 
Beans 
84*9 
29*5 
The data obtained in the course of these experiments show clearly the kind of fodder 
supplied to the animal exercises profound influence on the composition of the fat produced, 
and it is remarkable that the food-material of such similar compositions as pease and beans 
should, in animal metabolism, give rise to such differences as are shown in the foregoing 
table. The practical investigation of the matter has, however, been carried on on a suffi- 
ciently large scale to afford conclusive and reliable results, and the production of bacon of the 
required quality would appear in the future to depend on the farmers adopting the fodders 
which produce least olein. 
THE USE OF OZONE FOR STERILISING WATER. 
Ozonised air has long been known to be a very efficient steriliser for water, although 
the dry gas has been found to possess little bactericidal power. Its use has, therefore, 
been suggested for the purification of potable waters, but the early experimental installations, 
which were erected at Blankenburg, Oudshorn and Paris, are reported to have been 
abandoned, and at present the process is only known to be in operation at Lille in France, 
at Bole in Mexico, and at Moscow in Russia. The method is a simple one, but hitherto 
the cost has been a considerable factor against it, though upon this point it has been difficult 
to get trustworthy figures. Recently, however, the process has attracted renewed interest, 
and one of the London water companies is at present conducting experiments with a view to 
introducing it here. Considerable interest, therefore, attaches to the publication of details 
regarding the %vorking of the small experimental installation which was erected by 
Siemens and Halske, at Martinikenfelde, near Berlin, in 1898. 
The ozonisers employed here are of the Siemens and Halske plate and tube type, and 
yield from 20 to 25 grams of ozone per E.H.P. hour, with an E.M.F. of 12,000 volts. 
Air is first forced through a drying chamber and then passes into the ozonisers, on 
leaving which it contains from 2 '5 to 3 grams of ozone per cubic metre. It is then led 
to the base of the sterilising tower, a square structure packed with flints, and as it rises 
through these it meets a descending stream of the water to be sterilised, which has undergone 
preliminary filtration through sand. The plant in question is capable of treating 240 cubic 
metres of water in 24 hours (1 cubic metre is equal to about 220 gallons), and the results of 
the exposure to ozonised air will be seen from the following tests made with water from the 
River Spree. With a consumption of two grams of ozone per cubic metre of water, the 
number of bacteria per cubic centimetre was reduced from 600,000 to 10 ; the permanganate 
absorption figure was diminished by 18 per cent., and the aeration of the water was increased 
from 10 to 12 per cent. 
I he capital outlay for an installation capable of treating 150 cubic metres of water per 
hour is estimated to be ,£6,750, of which total the ozonisers and sterilising tower absorb 
£ 3 > 75 °- The actual cost of treatment for a plant of this size is given as I '726 pfg. per cubic 
metre, and the total cost, including interest and depreciation, amounts to 5 '031 pfg. per 
cubic metre, the latter figure being equivalent to about £ 1 1 per million gallons. 
In addition it may be noted that Siemens and Halske have recently patented a method 
of clearing turbid water by the combined action of ozone and iron. 
THE TREATMENT OF AURIFEROUS MISPICKEL ORES. 
The ores worked at the Deloro Mine, in Ontario, are derived from several veins, the 
two principal being the Gatling and the Tuttle lodes, where the ore consists of quartz heavily 
impregnated with mispickel, and occasionally chaleopyrite and iron pyrites. It is treated both 
for its gold and arsenic contents. Other veins in which the ore is oxidized are being worked, 
and it is necessary to treat them in a different manner. The strike of the veins is nearly 
north and south, whilst the dip varies from 45 0 to 63° to the horizon. The average width of 
the Gatling lode is 4 to 5 feet, and the wall rock is talcose schist or diorite, the latter being 
the country rock. The fine crushing is performed by means of a series of stamps, with a 
capacity of 4 tons per day. As much of the free gold as possible is caught by amalgamation, 
the amount so obtained being generally 57 per cent, of the assay value. The pulp, after 
leaving the plates, is passed over 6 feet corrugated belt Frue Vanners, by means of which the 
sulphides and coarser particles are separated. These concentrates consist chiefly of mispickel 
with some iron pyrites, small amounts of copper, and 15 to 20 per cent, of quartz sand. The 
latter renders the dense concentrates more readily leachable. For leaching 2 lb. of potassium 
cyanide and a lb. of cyanogen bromide are used per ton of concentrates, and Lhe gold is pre- 
cipitated from solution by means of zinc dust, of which 19 lb. is consumed per ton of concen- 
trates, By these solutions an average of 90 -5 per cent, of the gold content is extracted. 
After separation of the gold the concentrates are calcined for arsenic, and the arsenious oxide 
obtained after resublimation is quite white and practically pure. The production of the 
latter is 40 to 50 tons a month, which is the total American output of this material. 
