Energiatgpe, a new Photographic ~Procees. 2 ~ 3

its level, and the Hersehei mark refixed and filled in with eemetlt, i t was necessary to erect heavy shears of large spars, to place the stolI~a of tlle obelisk, composed of large blocks of Craigteith stone, sot~te weigtfing two tons. Tiffs was accomplished with some trouble a r i d expense, and the base of the obelisk was laid with the faces c o r t e s . l)onding with the four cardinal points. The whole was completed o t i the 15til of February, 1842, in presence of some of the commit tee , and several of the subscribers and fl'iends of Sir ,lohn Herschel, w h o attended on the oeeasion of placing the top stone of the obelisk. T h e obelisk has the base 6 ii~ct square by 6 feet iu height, and tile p y r a - midal part stands 1~? feet above the base. On the east face is a n opelfing showing the ltersehel mark, designatiag Iho aite of the 2 0 feet reileetor. The opening wilt be dosed with a bronze plate, c o n - taiui~g the inscription of the purpose for which the obelisk is erected. , , ~P roc . ,,,tslrom See., Lend. Ibid.

],2ne~),¢i(~dyt;e , a new P/telegraphic Proce,gs. B~j Ro1~Fm'r Hu~'r .

While pursrting some investigations, with a view to determine t i le influence of the solar rays upon precipitation, I have been led to t h e discovery ef a new p}lotographic agent, which can be employed iu the preparation of paper with a facility which no other sensitive p r o - eess possesses. ]Icing desh'ous of affording all the in.formatiou .t possibly can to lhose who are anxious to avait themselves of t h e advautages offered by photography, I solicit a little space in y o u r columns ibr the purpose of publishing the particulars of this n e w process. All th~ photographic p'oc¢sses with which we are at p r e - sent aequain{ed, sufficiently sensitive tbr the fixation of the images o[" the camera obsenra, require the most caretitl and precise manipula- tion; consequently, those who are not accustomed to the niceties o f experimental pursuits, are frequently annoyed by l'ailures. The t¥)l- lowing statement will at once show the exceeding simplicity of t h e new discovery.

Good letter paper is first washed over with the following solution : A saturated solulion of sueeinie acid, 2 drachms. Mucilage of gum arabic, ~ " Water, 14 "

When the paper is dry, it is washed over once with an argentine s o - ]tttion, consisting of one drachm of nitrate of silver to one ounce, o f distilled water. The paper is allowed to dry in the dark, and it is f i t for use. It can be preserved in a port-folio, and at any time e m - ployed in the camera. This paper is a pure white, and it retains i ts color, which is a groat advantage. At present I find it necessary to expose this prepared paper in the eamera obseura for perioda v a r y i n g with the quamity of sunshine, from two Io eight minutes, a l though, from some results which I have obtained, I am satisfied that, b y a nice adjustment of the proportions of" the materials, a much sho r t e r exposure will sutliee. When the paper is removed from the c a m e r a , no trace of a picture is visible. We have then to mix together o n e

284 Mechanics, Physics, and Chemistr!l. drachm of a saturated solution of snlphate of iron, and two or three drachms of the mucilage of gum arabic. A wide, flat brush, saturated with this solution, is now swept over the face of the paper rapidly and evenly. In a few seconds the dormant images are seen to develop themselves, and with great rapidity a pleasing negative photographic picture is produced. The iron solution is to be washed off as soon as the best eilL, ct appears, this being done with a soft sponge and clean water. T h e drawi .g is then soaked for a short time in water, and may be pcrmaue~lly fixed by being washed over with ammonia, or perhaps bettm with a sotntion of tim hyposulphite of sods, care being taken lhat the sail is afterwards well washed out of the paper. From the pielure thus produced, any number of others, correct in position, aud in light aml sha(low~ may be produced, by rising the same st|ecinated l~a[mrs in the ordinary way, from five (o fen minutes in sunshine prr)duch~g lhe (h'sir(xt eflimt.

The advantag~-s whM~ tiffs process possesses over every other nlilSt be, t lhink, alfl)'ar(:nl. Th(: papers are prepared iu the most simple lllallllet'~ itlid lllav bC I<cpt rea(lv by tim lourist mlti[ required for use. They require no !)l 'Cpal'alioil l)l:eviously to their being placed in lhc catn~:ra~ amt t}w M can })e preserved m~ti[ a convenient opporttmity ofthrs for l)rillging mlt the picture, which is done in the most simple l l ta tnler , with a ma.tt+riaI which can be any where procured.

Anxious to givc. the public lhe advautage (of thi.e proet:ss duril~g the be;ttltil'~ll we:tiber ()t"th~; prcseBt season, I have tier ~v'aited to perfi~et lhe mal~it)u!atory (h:lails which arc. uecessaay for the production of portraits. I~i:, >uiliciel;t, howovcr, lo say, that experiment has salis- fled me of it,~ ;~ppiical~ilily for this purpose.

Prismalic cx~rui~mtiou has proved that the rays effeeting this chemical chauge, are those which t have elsewhere shown to be per- feetly independent of solar light, or heat. I, therefore, propose to distinguish thi::; process by a name which has a general, rail:el" than a particular, application. Regarding afl photographic phenomena as due to the pri~miple Ene~\gia, I would, l~everthetess, wish to distin- guish this very i~teres|ing process as the E~zergiaQ/pe

I enclose you a few specimens of the resalis already obtained. The exceeding sensibility of lhe Energiatype is best s/lown by an attempt to copy engraviugs, or leaves, b v it. The three specimeus I enclose, were produced by an exposure of considerably less than oue second. --.qt/~enwum.

In a subsequent number of the "Athenmum," Mr. Hunt has givet~ the .%llowing additional direetions:-~

Experience has suggested to me the advantage of adding to the solution of suceinie acid and gum, as previously given, five grains of common sail. This preserves tim lights very clear, and, indeed, im- proves the sensibility of the paper.

When the solution of" the snlphate of iron is laid over the paper, it is requisite {o keep disturbing it, by rapidly, but lightly, brushing i~ up; otherwise mmmrous little black specks form, which destroy the photograph. If, as sometimes happens, the surface of" the picture blackens all over, it must not be concluded that the drawing is des-

On Preserving Salts for the Microscope. ~85 T troyed, he whole of this superficial blackness may be removed by

immediately washing with a wet sponge. I f the lights become ia any way discolored, a little exceedingly diluted hydrochloric (muri- atic) acid will restore them to their proper degree of whiteness; but care must be taken that the acid is speedily washed off, or the shadows will suffer.

When, from the shortness of the exposure, the image develops itself slowly, or imperfectly, a slight degree of warmth brings out the pie- lure with rapidity and force. Holding the paper a short distance from the fire is the best mode of operating.

Lond. Rep(~r. Pat. Inven.

Nole o~ a Means of Preservin~ the Crystals of galls as permanent ob/ecls Jbr ~]/iicroscopic Invesl@ation. By ROBERT WAI~nlN~- TON, .Es(/. "~'

Ilaving occasion lately to require the crystals of various salts, ill a state fitted fbr examination, by polarized light under the microscope, aml as the preparation of these crystals was frequently attended with much tronble and loss of time, it became a point of importance to render the object, when once perfected, permanent, so that the inves- tigation of certain individual crystals could be repeated, and additional observations made at any period. This was rendered ttle more desir- able from the difficulty of obtaining perfect and isolated subjects, and the rapidity with which many of these undergo alteration by exposure to the air. With some few salts this operation was comparatively easy, as the Canada balsam offered an excellent medium for the pur- pose, but in the greater number of cases I have examined, it proved totally indifferent ; and this arises from two causes, the first from the action of the turpentine contained in lhe balsam rendering the surfaces of the erystats opalescent; the second, from the heat, w.hich it was necessary to apply to make the balsam sufIieier)tly fluid to displace the atmospheric air, fusing the salt in its water .of crystalization, or rendering it opake fi'om the loss of water. Olive oil on trial appeared a good medium for all eases, but was objectionable from its fluidity, and from its depositing its stearine in cold weather. Castor oil was then tried, and this I have adopted with great satisfaction.

The method to be adopted it). mounting these specimens is as fol- !ows:--A warm saturated solution of the salt required is to be pre- pared, and a drop of it placed upon the glass slider, on which it is intended to be permanently mounted, and allowed to crystalize; when a good group of crystals is obtained, the uncrystalized portion is to be cautiously removed ; this is best effected by drawing it grad- ually away in a small stream along the edge of the slider, having previously broken through that part of the erystaline ring adjacent to the edge; the salt is to be allowed to drain itself quite dry by" placing the slider on its end in a vertical position. It should next be examined under the microscope, to ascertain the fitness of the crystals for the

Communicated by the Chemical Society; having bean read January 15, 1844.