Alan Douglas collection, lamp on left believed to be made by Crookes

 

Pharmaceutical Journal: A Weekly Record of Pharmacy and Allied Sciences 1883 "Mr. William Crookes, F.R.S., who has sold his lamp to the Gülcher Electric Light Company, takes cellulose, which he purifies by soaking in hydrofluoric acid, etc. He also claims the use of certain substances which are capable of absorbing the residual gas; he mentions thorina and alumina as suitable for this purpose. It is stated in the specification, No. 1422, 1881, that alumina absorbs residual traces of aqueous vapour. The method of utilizing this property is thus given:- After exposing the substance to the action of aqueous vapour the containing bulb is to be exhausted in the usual way until the exhaustion reaches, say, the one ten-thousandth of an atmosphere. On applying heat to the part of the glass containing the alumina occluded aqueous vapour is given off from the alumina. On re-exhausting as completely as possible a mere trace of vapour is left in the bulb; as the heated alumina cools down this residual trace of vapour is absorbed, thus rendering the vacuum practically complete. Mr. Crookes says that by operating in this way it is easy to push the exhaustion to a degree that would be impracticable by the use of a pump only. The vacuum thus produced will prevent an induction spark passing that would strike through several inches of air. The methods by which the purified cellulose is formed into filaments constitutes another patent, No. 2612, 1881. In this specification several different ways are given of treating the purified cellulose with an ammoniacal solution of cupric hydrate called cuprammonia, a well-known solvent of cellulose. In the first method the cellulose is taken in a manufactured form as thread, paper, etc. The material is passed through or dipped into the solvent for a few moments until the cellulose is acted upon to such an extent as wholly or partially to destroy its intimate structure, but not sufficiently to produce disintegration or solution. When sufficiently acted upon the material is allowed to dry by simple exposure to the air. The copper that remains behind is extracted with dilute acid; after extraction the material is washed thoroughly with water and dried between sheets of blotting paper. Another process is to allow a cuprammonia solution of cellulose to evaporate in a shallow dish, with an accurately levelled plane bottom. When the skin or film left has acquired a sufficient consistency it is treated with dilute acid to extract the copper, thoroughly washed with water and dried under pressure between sheets of blotting paper. The filament is prepared from the above material by cutting or punching out an adequate portion. The ends of the filament are strengthened by electro- depositing nickel or copper on them, and the junction between the conducting wires and the filament are painted with a thick syrupy cuprammonia solution of cellulose; after drying and carbonizing a good junction will be obtained possessing good conductivity from the finely divided metallic copper present. The carbonization is to be effected slowly in a gas muffle furnace, the filaments being buried in powdered charcoal and placed under moderate pressure during the operation, coal-gas is passed through the iron box in which the filaments are carbonized during the whole operation. If the filament after carbonization does not possess the right resistance or is imperfect, it is improved by heating it in a vacuous vessel containing a quantity of a high boiling point hydrocarbon, of which the vapour tension at ordinary temperature is low, such as naphthaline, or xylol or chloroform. These hydrocarbons, although present in quantity, emit an attenuated vapour, which is slowly decomposed and deposits carbon on or in the pores of the filament in a good conducting graphitoidal form. The manner in which the filament is mounted in its glass globe forms the subject-matter of another patent, 3799, 1881. This patent specification contains an interesting description of the manner of forming the glass envelope, which, however, could not be intelligibly described without the accompanying diagrams. The most notable feature is the device of using a cored wire conductor for sealing into the lamp. It is difficult to make a good junction between the glass and the metal except in the case of platinum; and with thin conducting wires of platinum the low conductivity of the metal causes it to heat when large currents are used, and to crack the glass or cause a leak at the junction. Mr. Crookes gets over this difficulty by using a compound wire having a core of copper, silver, gold, or other good conductor, and a platinum sheathing, so that there is the advantage either of using a cheaper metallic conductor or a metallic conductor of better conductivity, without any increased difficulty in making it form a good junction with the glass."

 

The Principles and Practice of Electric Lighting by Alan Archibald Campbell Swinton 1884 "The Crookes Lamp. The Crookes lamp, the invention of Mr. William Crookes, F.R.S., is characterised by its durability and economy in working. The main features of the lamp are a carbon filament, an exhausted globe containing the latter, and a contact socket. The filament is manufactured out of cellulose or vegetable fibre, from which all traces of silica, lime, iron, and other inorganic constituents are removed by treatment with hydrofluoric acid in which these substances-which if allowed to remain lead to the disintegration of the filament-are soluble. A solution of cuprammonia is then used to destroy the structure of the cellulose and to render it homogeneous. After carbonisation the filament is absolutely structureless, and is very dense, hard, and elastic. The filament, which is bent in the form of an M with rounded corners, is attached to two small platinum wires, the junction being effected by painting the joints of contact with a special carbonaceous cement. Imperfections in the carbonised filament are repaired and its resistance reduced by submitting the filament, in a state of incandescence, to the action of an attenuated atmosphere of chloroform, chloride of carbon, or hydrocarbon, from which carbon is slowly deposited upon the weak places. The glass globes are manufactured according to a novel process by means of machinery, the expense of the operation being remarkably low. The vacuum requisite for the durability of the filament is obtained by a modified form of Sprengel pump, and the final exhaustion is got through the employment of an earthy substance having a high affinity for aqueous vapours and other gases, this substance being introduced into part of the pump and, after the exhaustion has proceeded some length, heated so as to drive off the gas that it has absorbed. After further exhaustion the earthy substance on cooling absorbs the greater part of the remaining gases, and the lamp is sealed up, thus producing a vacuum higher than that obtainable by any other means. At the base of the lamp a neat socket arrangement is provided, which is so made that by a half-turn of the lamp in either direction contact with the leading wires is made or broken, and the lamp lighted or extinguished. These lamps are made from 4 to 50 candle-power and to work with an E.M.F. of from 10 to 120 volts, and require 60 watts for 20 candles."

 

The Fisheries Exhibition Literature, Volume XII 1884

 

North of England Institute of Mining and Mechanical Engineers, Transactions, Vol. XXXIV 1884-1885 1885 "The Crookes lamp, owned by the Giilcher Company, presented many good features, particularly in the strength of the glass, but it seems not to have made much way.* *The writer learns that the directors of the Gülcher Company have definitely abandoned the manufacture of the Crookes lamp."

 

Related links:

• Sir William Crookes, Ed Covington
• A photo of a Crookes incandescent lamp can be viewed in Two Small Collections of Early Lamps, Ed Covington