416 
Scientific Intelligence.- — Arts, 
which the plates are executed in zinc. It is a collection of mo* 
numents of architecture, which will consist of twenty numbers. 
The work is done on zinc in the same manner as on stone, and 
the expence of engraving is thus avoided ; hence the publisher 
has been enabled to sell the number, consisting of twelve folio 
plates, at five francs upon common paper. In an economical 
point of vievv, this method, therefore, deserves to be recommend- 
ed. We see by the German journals, that M. Eberhard, au- 
thor of the collection in question, has recently published a 
pamphlet upon the use of zinc, with the view of replacing cop- 
perplates and lithographic stones, for engraving and design- 
ing; 8vo. with 10 plates, Darmstadt 1824. 
26. Observation regarding the Alcanna of the Orientals, or 
Egyptian Henne. — M. Virey having received some of the pow- 
der of henne, sent to him from Egypt, is induced to publish 
some remarks upon the employment of this cosmetic and tinctorial 
vegetable, the use of which is extremely ancient in all the coun- 
tries of the east, for dyeing the fingers and nails, and sometimes 
the feet, of women. This practice has been so extended over 
the globe, with the conquests and religion of the Arabians, that 
it is found to exist at the present day from Damietta to Macao. 
It is used for dyeing skins and maroquins of a reddish-yellow. 
Messrs Berthollet and Descotils have not found any tannin in it, 
although it precipitates sulphate of iron black, which indicates 
the presence of gallic acid. The acids diminish its reddish-yel- 
low colour, the alkalies deepen it. According to the above-men- 
tioned chemists, wool may be died with the henne of a good 
yellowish red or brown colour. An orange-red colour is also 
extracted by alcohol. According to Russel and Forskal, it is 
sufficient to apply to the skin the leaves of the henae, beaten to 
a paste, and rub it with the hands when it is wished to colour 
it. Old women tinge their hair brown in the same manner, 
and some old men of the lower sort the beard also, when it has 
grown white. When it is wished to render this colour more 
brown, the juice of green nuts is added. 
27. Native Oil of Laurel used in Spanish Guyana, — The 
inhabitants of Spanish Guyana extract, under the name of Azeyte 
de Sassafras, an oil from a species of tree of the natural family 
of Laurels. This tree abounds in the forests of Parimia, and on 
