Oct. 20, 1870] 
NATURE 
497 
and history, for French and German, and for a careful study of 
English literature and language, we assert that by improved 
methods, by dexterous timing, and by greatly increased personal 
labour, we teach these new subjects thoroughly, and by no means 
neglect the old ones.” 
Engineering records the death, on the 16th inst., at New 
York, of Mr. Thomas Ewbank, the well-known writer on 
hydraulics. He was born at Barnard Castle, England, in 1792, 
and, after being apprenticed to a tin and coppersmith, came to 
London, where’ he spent all his spare time in scientific study. 
In 1819, being then a member of several learned societies, he 
emigrated to New York, where he was engaged for seventeen 
years in business as a manufacturer of lead, tin, and copper 
tubing, which occupation he relinquished in 1836 for purely 
scientific work. Besides contributions to scientific journals, and 
labours on various Government scientific committees, Mr, Ewbank 
was the author of ‘‘ A Descriptive and Historical Account of 
Hydraulic and other Machines for Raising Water, beth Ancient 
and Modern ;” “The World a Workshop, or the Physical Rela- 
tion of Man to the Earth;” ‘‘ Life in Brazil, or the Land of the 
Cocoa and the Palm ;” and numerous smaller publications. 
THE United States steamer Kansas, now fitting out at the 
Washington Navy Yard for duty on the Tehuantepec and 
Nicaragua Expedition, was, according to Engineering, put in 
commission about a fortnight ago. The Aazsas will be the 
principal vessel of the expedition. The survey in Nicaragua 
will embrace the route for a canal advocated thirty years ago by 
the Emperor Napoleon. That in Mexico by the Tehuantepec 
river possesses less interest, owing to the length and difficulties 
of the route. 
THE first quarterly number of the Yournal of the Iron and Steel 
Institute is announced to appear with the new year. 
Mr. ADOLPH HUBNER read an interesting and valuable paper 
on scientific observation in the interior of Port Natal, at a 
meeting of the Natural History Association of that colony on 
the 2oth of August. 
ON the 8th August Mr. S. Vincent Erskine read a paper be- 
fore the Natal Natural History Society—Mr. John Robinson in 
the chair—on the Tsetse Fly. Mr. Erskine severely criticised 
Dr, Livingstone’s statements, and denied that the fly was destruc- 
tive to the life of the ox, horse, or dog. He affirmed that 
death was to be attributed more to change of grass or climate. 
The same evening Mr. Morant read a paper on the Entomology 
of the Free State and the Trans Vaal, particularly with regard 
to the butterflies. 
THE expedition of Yale College students, under the leadership 
of Prof. O. E. Marsh, to which we referred last week, spent 
several months in the Rocky Mountain regions, investigating its 
flora and fauna, and collecting for the Yale Museum as fine co]- 
lections as possible of the extinct animal remains found in such 
abundance in the tertiaries and cretaceous deposits of Nebraska, 
Dakota, and Wyoming. Leaving this region they will visit 
California, and after investigating the geology of the Pacific 
coast, will return through Colorado and Kansas, reaching New 
Haven, if possible, in November. 
COCOA 
OCOA is a valuable article of food that is becoming 
more and more in use in this country, and judging 
from the increased importations during the past three or 
four years, and the constant average of the coffee imports 
during the same period, it seems that cocoa is, in a mea- 
sure, displacing coffee as a popular beverage. , 
The plant producing the cocoa of commerce is a tree 
seldom growing toa greater height than 17 or 18 feet. It 
is known to botanists as Theobroma Cacao. It bears an 
oblong fruit, ribbed longitudinally, measuring from six 
to teninches in length and four to five inches across, and, 
when ripe, is of a yellow colour, changing to brown in 
drying. 
It contains from fifty to one hundred seeds, and these 
seeds, after being washed, thoroughly’ dried in the sun, 
and roasted, form the cocoa-nibs of commerce. 
Linnzeus must have had a high appreciation of cocoa 
when he gave to the genus the name Theobroma, which 
is derived from ¢heos, god, and droma, food, signifying it 
as food fit for a god. Cocoa contains a large amount of 
nutritive matter. In this respect it differs in a marked 
degree from tea and coffee; for while they are taken only 
in infusion and are used as refreshing beverages, cocoa 
is usually taken more in substance, and, as such, may be 
considered both as food and drink. 
It was used in very early times in Mexico, whence 
it was introduced by the Spaniards into Europe about 
1520. Humboldt tells us that it was extensively culti- 
vated in the time of Montezuma, and the seeds were 
commonly used as money by the Aztecs. At the pre- 
sent time the cocoa-tree is largely grown in the West 
Indies, more especially in Trinidad, and over a great 
part of tropical America. Numerous varieties of the 
cocoa tree exist, some producing longer, or broader and 
some thinner or thicker skinned fruits, others producing 
larger, longer, or broader seeds, asthe casemay be. The 
seeds also vary in quality, according to the variety pro- 
ducing them or the place of their growth: thus Carac- 
cas and Trinidad seeds are considered the finest, and 
some manufacturers use the names of the best districts 
as a recommendation to their wares. 
The seeds are brought into this country in a dried state, 
and are roasted in revolving metal cylinders, the heat 
causes them to shrivel slightly so that the husks or skins 
are left loose and are removed by fanning. It is said that 
large quantities of these husks are imported from Italy 
under the name of “ Miserable,” and are used in Ireland 
by the poorer classes. The roasted seeds, after the husks 
are removed, are known as cocoa-nibs, but they are never 
seen in commerce in their whole form. The seed naturally 
divides by its two cotyledons, and in the process of win- 
nowing each cotyledon gets broken into two or more 
pieces. To obtain the nibs and boil them in the old- 
fashioned way is certainly the surest way of getting 
genuine cocoa, 
Some trouble, however, attends the preparation of the 
beverage in this form, the nibs requiring to be boiled an 
hour or two to extract their valuable properties. To obviate 
this, and to supply the public with a more convenient 
article, powdered cocoas, which require simply mixing with 
cold milk, boiling water being afterwards added, were 
introduced. These prepared cocoas opened a wide ficld 
for wholesale adulteration, the public, by using them, 
sacrificing purity for convenience in the preparation jor 
the table. 
These powdered cocoas are “prepared” by reducing 
the seeds to a fine paste by grinding them under heavy 
heated rollers—starch, flour, sugar, molasses, and, in the 
cheaper kinds, other ingredients less wholesome being 
added ; after which, the whole mass is reduced to powder, 
packed in different forms, and sold under various trade 
terms, such as “ Homeceopathic Cocoa,” “ Soluble Cocoa,” 
&c. Each manufacturers individual preparation varies 
perhaps in flavour, according to the proportion or character 
of the ingredients added, The numerous forms of cake 
chocolate are prepared in the same way, vanilla being 
largely used in the flavouring, and the pasty mass being 
pressed into moulds instead of being reduced to powder. 
Rock cocoa and Flake cocoa are likewise prepared in a 
similar way, but are not so highly flavoured. 
Few articles are more liable to adulteration than cocoa; 
and so many forms or qualities are known in trade, varying 
in price from 6¢. up to 4s- per lb., that it is not surprising that 
in the cheapest forms the adulterants themselves should be 
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