78 
HEW SILK MOTH. 
The use of quartz is preferable to that of bichromate of potash, because the mass 
caunot fuse, and is not liable to projections. 
The presence of chlorides and sulphates does not affect the process, the nitrates alone 
being decomposed. Amorphous and crystalline silica are identical in their action. 
Silica may also replace bichromate of potash in estimating carbonic acid. To expel 
all the carbonic acid, a greater heat is required than for the decomposition of the ni¬ 
trates. The bright red-heat afforded by a Bunsen burner is however always sufficient. 
— Poggendorff’s Annalen. 
RESEARCHES ON HENNA. 
BY M. ABD-EL-AZIZ HERRAONY, OF CAIRO, EGYPT. 
The author, a graduate of the School of Pharmacy of Paris, selected Henna as the 
subject of his thesis. Henna ( Lawsonia inermis ) is a plant which has been known to the 
people of the East from the highest antiquity. The leaves are employed either as a me¬ 
dicine or in the preparation of certain cosmetics. Its flowers, possessing equal medicinal 
virtue, are used as an agreeable perfume. They are sold in Cairo, as the lilac is in Paris. 
Henna is common in the East Indies, at Malabar, Ceylon, etc., and in Arabia, 
Persia, and Egypt, where it is very abundant. The author admits of only one species— 
Lawsonia alba , of which there are two varieties, L. inermis and L. spinosa. The leaves 
are employed as a topical application to ulcers of the mouth, and for staining the feet, 
hands, and hair. This use is perhaps less the result of coquetry than to avoid 
certain skin diseases, so common in hot countries. The leaves are also used for dyeing 
light-coloured woods of a mahogany colour. The fruit is considered emmenagogue. 
Henna is furnished to commerce in the form of powder. Two sorts are distin¬ 
guished ; Henna of Arabia, and Henna of Egypt, the latter least esteemed. The 
former is often adulterated with sand and Egyptian henna, so as to be about equal in 
dyeing value to the latter. 
The author in his chemical examination has aimed at isolating the active colouring- 
principle. Cold water does not extract it, but it is removed by boiling water. Ether 
does not remove it, but extracts the chlorophyll. Alcohol of ninety per cent, com¬ 
pletely extracts it by percolation ; and when the alcohol is distilled off from the tinc¬ 
ture, the syrupy residue exhausted by ether, and the residue again treated by strong 
alcohol, and evaporated, the active matter is obtained. 
The principle is brown, of a resinoid appearance, and soluble in boiling water. It 
possesses the properties of tannin, such as blackening the sesqui-salts of iron and pre¬ 
cipitating gelatine. It reduces oxide of copper in Troinmer’s test, and heat decomposes 
it with the evolution of crystalline needles, which reduce nitrate of silver. The colour¬ 
ing matter of henna is therefore a species of tannin, and the author has named it 
henno-tannic acid. 
The author made various experiments with henna as a dye-stuff, for silk and woollen, 
with results favourable to the permanence of the shades of colour produced.— Journal 
de Pharmacie , Jan. 1863. 
NEW SILK MOTH. 
The introduction of a new Silk Moth ( Bornbyx Cynthia ) into Europe bids fair to 
be of great importance. It was first sent from China to Turin by a Piedmontese 
missionary in 1857, and so early as 1858 it had attracted the attention of Guerin- 
Meneville at Paris, so far as to induce him to plant 5000 trees of Ailanthus glandu- 
losa , on the leaves of which the caterpillar feeds. It is reported that the almost incre¬ 
dible quantity of 100 millions of trees are now planted in France for the sustenance of 
the caterpillar, insomuch that Guerin-Meneville has said that “ Henry IV. gave us 
silk for the rich, but Napoleon III. has given silk to the poor.” 
We believe, indeed, with every reader of ‘ Quentm Durward,’* that silk was pro¬ 
duced in France long before the reign of Henry IV.; but however this may be, the 
* Louis XI. is there spoken of as the great silk-merchant and cultivator of Mulberry- 
trees, under the name of Maxtre Pierre. 
