air When the seleniate of ammonia is heated, a little ammonia first rises, and then some selenic acid; but the greater part of the ammonia is decomposed; water and azote are produced, and the selenium remains in fusion, and may be afterwards sublimed. Seleniate of barytes is soluble in water, but scarcely so in alcohol. It crystallises first in needles, the extremities of which become covered with a pencil of smaller needles; after which the interstices gradually fill up, forming globular crystallised masses, the surfaces of which appear smooth and united, even under the microscope.

If a little muriatic acid be added to a solution of any seleniate, and a stick of zinc then inserted, the selenium falls down in a metallic forin: the zinc appears at first to. be covered with a pellicle of copper; after which the selenium is deposited in vermillion-coloured flocculi. If sulphuric acid is used instead of the muriatic, the preci-. pitate falls down more slowly, takes a grey colour, and contains sulphuret of selenium.

If a current of sulphuretted hydrogen be sent through a solution of selenic acid, the selenium is deposited of an orange-red colour, which becomes red by drying, melts in the fire, and may be sublimed into a transparent orange

mass.

These experiments will be sufficient to prove the existence of this peculiar and interesting substance. It is evidently derived from the Fahlun copper pyrites, in which M. Gahn has often remarked the peculiar smell of selenium, when the ore was roasting, but which he always attributed to some trace of tellurium. As the Fahlun pyrites used for the extraction of sulphur is largely mixed with galena, it is probable that this new metal may be. found in it under the form of seleniuret of lead. The proportion of selenium contained in this ore is very small;

500

500 pounds of sulphur burnt on the sulphuric acid cham bers yielded only one-third of a gramme of selenium. The sulphuric acid retains none of it, as the sulphureous acid! has the property of reducing the selenic acid to the metallic state.

On a new Species of Mineral Alkali discovered in the Petalite, by M. ARFREDSON. By M. VAUQUELIN. From LES ANNALES DE CHIMIE ET DE PHYSIQUE.

AVING received from M. Gillet Laumont ten.. grammes of the petalite, with a request to extract from it the alkali, and verify M. Arfredson's discovery of its peculiar properties, I undertook the task with eagerness. In confirming the observations of M. Arfredson, on the characters of this new alkali, which he has denominated lithion, I have added the following:

1. It has a caustic taste, like the other fixed alkalies, and strongly reddens vegetable blues.

2. It forms with sulphuric acid a salt that crystallises in small four-sided prisms, of a dazzling white, of a merely saline taste, not bitter like the sulphates of potash and soda, more soluble in water than sulphate of potash, and more fusible by heat.

3. It forms with nitric acid a deliquescent salt, of a pungent taste, which does not belong to the nitrates of potash or soda.

4. With carbonic acid it forms an efflorescent salt, of little solubility, though, much more so than the earthy carbonates. It may be precipitated from a strong sulphated solution by subcarbonate of potash. This gives a subcarbonate of selenium, which becomes saturated with carbonic acid by mere evaporation in the open air. This

carbonate

carbonate dissolves in about 100 parts of cold water, and this solution effervesces with acids, changes vegetable blues, precipitates muriate of lime and sulphate of magnesia and alumine in white flocculi, and the salts of copper, iron, and silver, in carbonates, exactly resembling those produced by the carbonates of potash and soda. It disengages ammonia from its saline compounds, yields its carbonic acid to lime and barytes, but does not precipitate muriate of platina.

5. Lithion, in uniting to sulphur, gives a yellow sulphuret, very soluble in water, which is decomposed by acids with the same appearances as the common alkaline sulphorets. From the abundance of the precipitate which acids produce, it appears that lithion saturates a large proportion of sulphur. To discover the capacity of saturation which this alkali possesses, and the proportion between its own oxygen and that of the acids which it neutralizes, I made the following experiments:

490 milligrammes of crystallised sulphate of lithion, melted in a gold crucible, were reduced to 430, which amounts to 12 per cent. of water. These 430 parts, decomposed by barytes, yielded 875 of sulphate of barytes, containing 297.5 of sulphuric acid, which makes the composition of sulphate of lithion to be 69.20 sulphuric acid, and 31.80 oxyd of lithion.

As the proportion between the oxygen of sulphuric acid and that of the bases which it saturates is known to be as three to one, and as the 69.20 sulphuric acid contain 41.52 oxygen, it follows (if the same law of saturation holds good here) that the 31.80 of oxyd of lithion contain 13.84 oxygen. Hence this oxyd must be composed of 56.50 lithion and 43.50 oxygen, in 100 parts; a proportion of oxygen which is much greater than in any other of the known alkalies:

List of Patents for Inventions, &c.

(Continued from Page 64.)

JEREMIAH SPENCER, of Great James-street, Bedford

row, Middlesex; for certain descriptions of fire grates; by which improvement the combustion of smoke is more easily effected. Dated December 5, 1818.

FREDERICK WILLIAM SEYFERT, of St. John-street, Clerkenwell, Middlesex, Watch-maker; for an improvement on certain descriptions of watches and clocks. Dated December 5, 1818.

MARK ISAMBAUD BRUNEL, of Chelsea, Middlesex, Civil Engineer; for a new species of tin foil, capable of being crystallised in large varied and beautiful crystallisation. Dated December 5, 1818.

JOHN WHITING, of Ipswich, Suffolk, Builder; for a window-shutter. Dated December 5, 1818.

HENRY PERSHOUSE, of Birmingham, Warwickshire, Factor; for a method of stamping pans for seals. Dated December 10, 1818.

JAMES BARRON, of Wells-street, Middlesex, Brassfounder; for an improvement in the making of knobs, generally used on drawers, doors, and cabinet furniture, and known by the name of drawer and mortice furniture knobs, or handles. Dated December 10, 1818.

DENIS JOHNSON, of 75, Long Acre, St. Martin-in-the Fields, Middlesex, Watch-maker; for a machine for the purpose of diminishing the labour and fatigue of persons in walking, and enabling them at the same time to use greater speed; which said machine he intends calling the Pedestrian Curricle. Communicated to him by a person residing abroad. Dated December 22, 1818.

Specification of the Patent granted to JAMES THOMSON, of Primrose Hill, near Clithero, in the County of Lancaster, Calico Printer; for certain Improvements in the Process of Printing Cloth made of Cotton or Linen, or both. Dated February 4, 1814.

To all to whom these presents shall come, &c. NÓW KNOW YE, that in pursuance of and in compliance with the said recited proviso, I the said James Thompson do thereby declare, that the nature of my said invention, and the manner in which the same is to be performed, is as hereinafter mentioned: The ordinary practice of Calico Printers is to apply with the block or pencil what are termed after-colours, to certain spaces originally left in their patterns and intended to receive the said after-colours, or to certain spaces on the cloth from which parts of the original pattern have been discharged, in order to admit by a subsequent operation the application of the said after-colours. Now the object of my invention is by one application of the block, cylinder, roller, plate, pencil, or other mode to remove parts of the original pattern or colour from the cloth, and at the VOL. XXXIV.-SECOND SERIES.

S

same