1853.1 



ELECTRIC LIGHT AND COLOUR MANUFACTURE. 



243 



hew motle of manufacturing colours, at a cost so insignificant as 

 to ensure a ready and inexhaustible market. Tliese are features 

 of exeituig interest; and, if fully realised as promised, must un- 

 doubtedly be attended with important consequences, by revolu- 

 tionizing the world of light and of colour. 



Mr. Watson freely acknowledges what is due to other elec- 

 trieians. He admits that Professor Daniel's galvanic battery is 

 distinguished for producing a continuous light; but from the ex- 

 pense of maintaining the action it could neier be profitably ap- 

 plied to common usjs, and was, therefore, a costly ornament, not 

 a marketable commodity. This great distinction is, of course, 

 fatal to its utility for the purposes of e\ery day life. Strongly 

 influenced by this impression, Mr. Watson turned his whole at- 

 tention to the finding of means of producing this light at a small 

 cost. We ai'e informed that he has fully succeeded in his object; 

 that he can produce and maintain this splendid light continuous- 

 ly for any required length of time, not only without cost, but ac- 

 tually at a profit, by the aid of a chemical transformation of the 

 elemeuts used in the working of the batteiy. These elements 

 liave hitherto consisted almost entirely of the common mineral 

 acids, zinc and copper: occasionally iron, leail, and tin were used, 

 but sparingly, and without any important acknowledged results. 

 Mr. Watson's new agents, or electrolytes, are only five in num- 

 ber, and from these he produces no less than 1 00 valuable paints 

 or 2>igments, of a superior quality and character, surjiassing in 

 marketable value the articles froni which they are produced, and 

 by which the light also is fed. It is, in fact, maintained that 

 not only is the light thus created without cost, but absolutely at 

 a profit, by the additional convertible value of the elements 

 transformed by the chemical process. The mode also of produc- 

 ing these colours is asserted to be not by nnj^ subsequent mix- 

 ture of the elements, but results from the actual development of 

 the electricity in the battery, the materials employed also aiding 

 in the galvanic ettect by gi\'ing constancy, from the want of 

 which united recommendations as Mr. Watson observes, the best 

 form af batteries at pi'esent in use are absolutely worthless for a 

 practical j^urpose such as lighting. 



The nature of the action thus produced, and the mode of the 

 process observed, is then touched on. We were also informed 

 that the Maynooth battery is the great fttvorite with electrical 

 experimenters, and that all the successful exhibitions of the elec- 

 trical light have been made with this battery. Without chang- 

 ing its foi'm, Mr. Watson has endeavoured to sujiplj^ its deficien- 

 cies, and render economical its working. 



He says: "Prussiate of potash, or, as it is known to chemists, 

 ferro-c)'anide of potassium, gives with the salts of iron a most 

 splendid blue pigment. — Prussian blue; which, when pure, is of 

 the greatest possible \-alue. In the Maynooth batteiy we em- 

 ploy the prussiate of potash thus : to the iron cell we add prusr 

 siate of potash, and to the zinc call also the same salt, although 

 we restrict the quantity greatly, for reasons which need not be 

 described here, but which to those having any acquaintance 

 with the nature of galvanic arrangements will be at once appa- 

 rent. Our products are Prussian blue, of a quality and colour 

 equal, or as we have been disinterestedly informed by those deal- 

 in the article, far superior to any in the market. Our other 

 product is a peculiar blue pigment, of a colour resembling, and 

 from specimens which may be seen at our manufactory at Wands- 

 worth, closely vying with the artificial ultramarines. This pig- 

 ment, from its chemical constitution, as proved by our analyses, 

 we have termed the ferro-prussiate of zinc. The insoluble na- 

 ture of these pigments, and their consequent removal from the 

 galvanic circuit by precipitation, gives to the Maynooth battery a 

 greater constanc}', as we have before described, than there remains 

 to it in its normal state. In addition to rendering profitable the 



working of the battery, the prussiate of potash has a distinct 

 galvanic action, in the manner before described. 



" The discoverer of the Maynooth battery is also the inventor 

 of another form of batteiy, of which we also have availed our- 

 selves for making colours. This form consists of platinised lead 

 and zinc, arranged jjrecisely in the manner ot a Sraee's l^atteiy, 

 and is similarly excited by nitro-sulphuric acid. In this batteiy 

 our ])igmeiits are chrome yellows, produced by adding the bi- 

 chromate of potash jirecisely in the same manner as with the 

 prussiate of potash. The depth and tint of the pigments, which 

 with chromes constitute their \'alue in the market, we \aiy with 

 the proportion of the salt added. As regards the galvanic eflfects 

 of the bi-chromate of potash, it is precisely the same as with the 

 IJrussiate of potash. 



" The power of the two forms of battery just described, and 

 their applicability to the purposes of electrical illumination, from 

 their constancy and intensity, will be best appreciated when it is 

 stated that a platin'sed lead battery is about fifteen times as pow- 

 erful as a common Wollaston battery of the same s"ze. A cast- 

 iron battery is a little less powerful than the platinised lead one, 

 but it is cheaper in its first erection, since the iron plates do not 

 require to be platinised. Three platinised lead batteries excited 

 by a solution of nitre and sulphuric acid, or three cast-iron bat- 

 teries excited by nitric and sulphuric acid, wilJ afford the most 

 brilliant light, equal, at least, to 300 wax candles, whilst it re- 

 quires 160 cells of Daniel's constant battery, or 250 of the ordi- 

 nary Wollaston battery, to eft'ect the same object. Three of the 

 lead or iron batteries will occupy just one-sixth the space occu- 

 pied by Daniel's arrangement, and one-twelfth of what is occu- 

 pied by WoUaston's. 



" The expense of constructing a platinised lead or iron battery 

 is far less than anj' of the other forms of battery in use. For in- 

 stance, a platinised lead or a plate of cast iron, of an efficient size, 

 may be had for Is., whilst a platina plate of the same dimensions 

 will cost nearly £3. Moreover, a platinised lead or cast-iron 

 battery, without any of the means by which we have eft'eeted an 

 economy, may be worked for one hour with a resultant of the 

 same power for one-tenth part of the expense of working a Grove's 

 batter}^ for the same time. 



" In addition to the cast iron and platinised lead batteries, we 

 employ a third form, which is identical in arrangement with the 

 old form of Wollaston batteiy, but free from the defects of that 

 instruments The sulphate of zinc, which usually attaches itself 

 in the form of metallic zinc to the copper-plate in WoUaston's 

 arrangement, after the battery has been in action a short time, 

 we find is carried down as a splendid blue pigment, much resem- 

 bling the better description of " smalts," by adding prussiate of 

 potash ; hence the constancy of the batteiy is maintained so long 

 as any fresh acid remains in the cells. 



" It will be easy to perceive that if prussiate of potash gives 

 with iron a blue colour, and chromate of potash with z'nc a yel- 

 low, that if these salts be added in a battery of iron and zinc — 

 the piussiate to the iron and the chromate to the zinc, the result- 

 ing products having access to each other through a diaphragm — 

 the colour produced will be a green, of a depth of tint dependent 

 on the quantity of the two normal colours tbrming the compound. 

 In like manner, b}' adding prussiate of potash to the lead battery, 

 a white ]iigment is jiroduced of great body, and perfectly free 

 from the fitult of blackening by exposure to sulphuretted hydro- 

 gen, the zinc seeming to act as a protective agent. If chromate 

 of potash alone be added to the iron batteiy, a deep brown colour 

 is produced. Lasth', if lime be added, with chromate of potash, 

 to the lead batteiy, a red pigment is produced, of gre.at brilliancy 

 and body. 



