September i, 1890 .] 
213 
THE TROPICAL AGRICULTURIST. 
■with the ground nibs, thus producing a cheaper articl® 
which is not so gross. Chocolate is merely cocoa to 
which a large quantity of sugar and more or less 
starch has been added, together often with various 
flavouring essences. Cocoa really partakes more of 
the nature of an article of food than of a beverage ; 
it is very rich in warmth-producing and flesh-forming 
constituents, and in these respects it compares favour- 
ably with tea and coffee. The term “ soluble cocoa ” 
is a misnomer : it should rather be “ miscible cocoa.” 
Anyone can demonstrate this by allowing a cup of 
cocoa to stand and settle for a few hours. The ex- 
periment is best performed in a glass tumbler. 
The mixture of cocoa are now made chiefly with 
sugar and starch, ami these are not regarded as 
adulterations by the manufacturers who make some 
of the “ prepared cocoas.” Venetian red, chicory, 
cocoa husks, and various flours and ground cereals 
are sometimes met with in low-grade cocoas ; but 
starch is “ the thing,” and to provide this the potato, 
sago, arrowroot, maize, &c„ are laid under contribution. 
Chocolate is made to contain a great deal of sugar, 
hence sophistication is more easily concealed from the 
taste. Chevalier states that chocolate is largely adul- 
terated, but that as the public generally understand 
that it is merely a preparation of cocoa, it does not 
much matter so long as the added ingredients are 
wholesome. Still there is no excuse for such substances 
as the following' being present, viz.: — Lime, ground 
lentils, maize and bean flour, foreign fats and oils, 
various gums, and such colouring matters as cinnabar, 
red earth, and even red had. Most of these sophisti- 
cations can be detected by the microscope if they be 
of vegetable origin, and if of mineral origin they can 
be identified by means of the usual chemical reagents. 
Wankljn states that the mineral matters ought never 
to exceed 5 per cent. He recommends the ditermination 
of the phosphoric acid in the ash as a means of 
detecting the adulteration. Fat is best estimated by 
extraction with ether. — Urocer. 
^ 
NOTES ON POPULAR SCIENCE. 
By Dit. J.E. Taylor, F. L. S-, F. G. S., &c., 
Editor of “Science Gossip,” &c. 
Whilst on the subject of chemical experiment, s 
and investigations of a pi actical character, I should do 
well to notice those on the physiological value of 
what may he termed “ commercial foods,” such as 
the ditt'erent kinds of oil-cake, &c., in relation to 
their milk -producing power. The experimental cow 
received 15 lb. of clover hay and 31b. of cake jier day. 
It was found that rape-cake produced an increased 
amount of milk the first day, and the same fact 
was recorded when this was exchanged for coconut 
cake. Indeed, in botli cases, the increase was very 
considerable, hut that produced by coconut cake 
lasted much the longer. In other experiments, in 
which 201 b. of green fodder was given per day, an 
addition of 3lb- of linseed cake gave an increase of 
12 per cent, of milk. The same weight of coconut 
cake raised the yield to 11 per cent, but lasted 
longer. Hemp-cake had no effect at all. The increase 
of milk was also produced by giving the cow (in- 
addition to its (ireen food) sun-flower cake, poppy- 
seed cake, coconut cake, &c.; the yield of milk 
being most increased by the la.st, and least by the 
sun-tiOwer seed cake.* 
Fob several years past I have been .suspicious about 
the use of nitrate of soda. Many farmers don’t know 
w)iat to do with it when they liave purchased it — and 
it is rather au expensive article. Artificial manures 
want mixing with the same sort of thing that Sir 
Joshua Reynolds said he mixed his paints with — 
brains. Then success is sure. I have long been of 
•This supplies a full and satisfactory answer to our 
question in diecussiug cattle disease and cattle feed, 
as to the suitability of coconut poonac for milch 
cowE.— E d. T. a. 
opinion that an excc.ssive use of nitrogen, whether 
organic or artificial, tended to promote and en- 
courge the rapid growth and development of such 
parasitic funguses as moulds, mildews, and rusts. 
Thus, in the published results of some Eothamsted 
experiments on the growth of potatoes, I observe 
that those manured by ammonium salts and soda 
nitrates, although they yielded splendid crops, had 
the largest proportions of diseased potatoes. What 
is the good of producing a diseased crop ? A manure 
of superphosphate of lime, although it only produced 
an average of three and a half tons of potatoes to 
the acre had only two and three-quarter hundred- 
weight of these diseased, whereas amniouiun salts 
and mixed mineral manure.s, and a mixture of sodium 
nitrate and other minerals, alihough they aciually 
produced a heavier crop of Potatoes (nearlv six tons 
in the former instance, and almost approximating to 
that in the latter), nevertheless yielded eight and a 
quarter and nine and a quarter hundredweights of 
diseased tubers respectively. The fact is nitrates of 
soda, as well as ammonium salts, in nearly every in- 
stance ought to be used sparingly (hand sown), and 
when the crop is just appearingSabove the ground. Then 
they are stimulants as well as food for th® baby p ants. 
Notwith^tanding my criticism regarding the use and 
abuse of nitrogenous manures, the above-mentioned 
Eothamsted experiments distinctly brought out the 
fact that the use of nitrogenous manure gives rise 
to a great increase of starch in the potato, just as 
in the ca.se. of root crops there is an increase of 
sugar ■under these conditions; and in that of cereals 
an increase of starch and cellulose. The real cause of 
the potato disease is the fact that the fungus converts 
its starch into sugar, and stores up in iise f a large 
proportion of the nitrogenous juices of the potato- 
The influence of the electric light upon vegetation 
has manifested itself in a very remarkable manner 
in the case of the large lime trees on the Leipziger 
Platz, Berlin. On the branches of those trees which 
are opposite the electric light, a few days ago the 
development of the new leaves had advanced con- 
siderably, whereas on the other side, where the light 
does not strike upon the branches the buds had only 
just j'leguu to form. 
I nave frequently referred to the idea of the late 
Professor Ville, of Vincennes, to the effect that the 
natural order of plants Leguminofss have the power 
directly to fix the nitrogen ot the, atmosphere. This 
appears also to be the belief of Sir John Lawes and 
Dr. Gilbert, based upon their experiments at Roth- 
amstead. It is further thought this nitrogen-absorb- 
ing power is largely brought about by the micro- 
organisms growing' on the roots of the Legu- 
mioosse. 
Here is a chance for wealthy young Australians 
to form a syndicate. M. Daubree, the well-known 
French geologist, has expressed his opinion that the 
deeper formation of the earth’s crust contain abun- 
dance of diamonds. Diamond powder, as I have al- 
ready shown, has been found in meteorites. Professor 
Daubree has made observations in all the diamond- 
bearing regions, and finds the stones occur in the 
oldest and most deeply-seated rocks. Why not start 
a company and bore down a mile or so? 
Two of our young and rising chemists — Messrs. H. 
T. Brown and G. H. Morris — have just given to the 
scientific world the results of a long-continued and 
most delicately manipulated series of experiments on 
the germination of some of the grasses. Their in- 
vestigation was undertaken with the view of throw, 
ing some light upon the complex metabolic processes 
which take place during the germination of seeds. 
This their first paper on the subject (read before the 
Chemical Society), is almost confined to barley. S ime 
years ago the great German botanist, Protessor Sachs 
rather startled the botanical wond by tbo statement 
that in a seed the relation of the embryo to the 
endosperm is that of parasite and host. Messrs. Brown 
and Morris’s experiments confirm Professor S^ehs” 
generalisa ion. More, in their experiment*, they availed 
themsalves of this suggested relation by cultiva'ing the 
embryo upon auitable media after Beparating it from 
