Zoology. 187 



species at the lead mines of St Turpet, in the Munster valley, near Frei- 

 burg, in Brisgaw. It occurs in yellowish-white small and short prisms, 

 and agrees, therefore, not only in its external appearance, but also in the 

 kind of its natural repository, with the Brewsterite from Strontian. 



24. Selenium from Lukawitz in Bohemia. — There is a considerable 

 manufactory of sulphuric acid, belonging to Prince Auersperg, at Luka- 

 witz, in the circle of Chrudim in Bohemia. The selenium, as at Grips- 

 holm in Sweden, is contained in the brownish mud deposited in the lead 

 chambers. According to the experiments of Frofessor Steinmann of Prague, 

 this mud contains about four per cent, of selenium. The ore employed 

 for extracting the sulphur is common iron pyrites, imbedded in mica- 

 slate. Professor Steinmann, who already possesses upwards of six ounces 

 of pure selenium, has contrived a method of concentration, by exposing a 

 mixture of this sediment, or of the sulphur containing selenium, extracted 

 from it by melting, and sulphuric acid, to a previous distillation. The 

 greatest portion of the sulphur is oxidized and driven off in the shape of 

 sulphurous acid, leaving a residue in which the con tent of selenium is pre- 

 dominant, to be treated afterwards, as usual, with nitro-muriatic acid. 

 Sulphur, containing about twenty per cent, of selenium, of a more or less 

 deep orange yellow, is sold at Prague, at the price of twelve shillings a 

 pound. Trials have been made, though hitherto unsuccessful ones, to 

 mould the selenium in basso-relievos, representing the portrait of Berzelius. 



25. Zircon found at Scalpay in Harris.— Mr William Nicol, Lecturer on 

 Natural Philosophy, has discovered fine crystals of Zircon in the primitive 

 rocks in the island of Scalpay, Harris. 



Zoology. 



26. Two-Headed Snakes.— DrMitchill of New York has recorded the cu- 

 rious fact of three double-headed serpents being found among a brood of 

 young ones amounting to one hundred and twenty. The occurrence of si- 

 milar monstrosities had led some naturalists to form the idea of these ano- 

 malous animals forming a separate and well marked species ; but two-head- 

 ed snakes being occasionally found in the West Indian and Polynesian 

 Isles, in Great Britain, in Italy, and in the State of New York, renders it 

 probable that these singular productions are not only of different species, 

 but of different genera; and that, in fact, the whole of the instances which 

 have been noticed, may be classed as deviations from the usual course of 

 nature. 



" During the year 1823 (says Dr Mitchill) a female snake was killed 

 about six miles west of the Genesee river, together with her whole brood of 

 young ones, amounting to one hundred and twenty. Of these, three were 

 monsters ; one with two distinct heads ; one with a double head, and only 

 three eyes ; and one with a double skull furnished with three eyes and 

 single lower jaw j— this last had two bodies. The figures, correctly drawn 

 from the origiin'ls in my collection, represent the shape M»d size of the scve- 



