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ssful； a perfectly black positive picture is at once developed。 At first it most commonly happens that the whole picture is sooty or dingy to such a degree that it is condemned as spoiled； but on keeping it between the leaves of a book； especially in a moist atmosphere； by extremely slow degrees this dinginess disappears； and the picture disengages itself with continually increasing sharpness and clearness； and acquires the exact effect of a copper…plate engraving on a paper more or less tinted with a pale yellow。
I ought to observe； that the best and most uniform specimens which I have procured have been on paper previously washed with certain preparations of uric acid； which is a very remarkable and powerful photographic element。 The intensity of the original negative picture is no criterion of what may be expected in the positive。 It is from the production by one and the same action of light； of either a positive or negative picture according to the subsequent manipulations； that I have designated the process； thus generally sketched out； by the term Amphitype；a name suggested by Mr。 Talbot； to whom I communicated this singular result； and to this process or class of processes （which I cannot doubt when pursued will lead to some very beautiful results；） I propose to restrict the name in question； though it applies even more appropriately to the following exceedingly curious and remarkable one； in which silver is concerned：
At the last meeting I announced a mode of producing； by means of a solution of silver； in conjunction with ferro…tartaric acid； a dormant picture brought into a forcible negative impression by the breath or moist air。 （See Cyanotype。） The solution then described； and which had at that time been prepared some weeks； I may here incidentally remark； has retained its limpidity and photogenic properties； quite unimpaired during the whole year since elapsed； and is now as sensitive as ever； a property of no small value。 Now； when a picture （for example an impression from an engraving） is taken on paper washed with this solution； it shows no sign of a picture on its back； whether that on its face is developed or not； but if； while the actinic influence is still fresh upon the face； （i。e。； as soon as it is removed from the light）； the back be exposed for a very few seconds to the sunshine； and then removed to a gloomy place； a positive picture； the exact complement of the negative one on the other side； though wanting of course in sharpness if the paper be thick； slowly and gradually makes its appearance there； and in half an hour or an hour acquires a considerable intensity。 I ought to mention that the 〃ferro…tartaric acid〃 in question is prepared by precipitating the ferro…tartrate of ammonia （ammonia…tartrate of iron） by acetate of lead； and decomposing the precipitate by dilute sulphuric acid。 When lead is used in the preparation of Amphitype paper； the parts upon which the light has acted are found to be in a very high degree rendered water proof。Sir J。 Herschel。
This process is a new invention of our countryman； J。 A。 Whipple； Esq。； of Boston； and has been patented by M。 A。 Root； Esq。； of Philadelphia。 It will be seen； however； from the previous pages of my work that Mr。 Root is mistaken in regard to his being the first improvement patented in this country； althongh it is unquestionably the first by an American。 Of this improvement Mr。 Root says：
VI。 〃CRAYON DAGUERREOTYPE。〃
〃The improvement to which you refer is denominated 〃The Crayon Daguerreotype。〃 This invention made by Mr。 J。 A。 Whipple； is the only improvement in Daguerreotyping； I believe； for which Letters Patent for the United States were ever issued。 The pictures produced by this processwhich is of the simplest description imaginablehave the appearance and effect of very fine 〃Crayon Drawings；〃 from which the improvement takes its name。 Some of our most distinguished artists have given it their unqualified admiration。 Among them； our Mezzotinto Engravers； especially John Sartain； Esq。； who； from his rich embellishments to most of the leading Magazines and Annuals of the country； as well as from the celebrity of the superb Magazine which bears his name； is so well known and so well qualified to judge of its merits。 As an auxiliary to the artist； in furnishing heads to the Magazines； or other works； it is invaluable； the great object which it accomplishes being to give a finer effect and more distinct expression to all the features the whole power of the instrument being directed to； and confined to the head。〃
〃The late hour at which this subject has been brought to our notice prevents so full a description as we would otherwise have been glad to furnish。 The New England States have been disposed of； negotiations for any of the others can be made through M。 A。 Root； 140 Chestnut street； Philadelphia。〃
〃A series of beautiful portraits are about being prepared by the 〃Crayton Process〃 for the express purpose of being placed on the exhibition at the 〃Art Union；〃 when amateurs； artists； and the public generally will have an opportunity of witnessing its effect。 We are especially gratified with this striking improvement； from the advantages which it promises to the Daguerrean art。〃
〃It is admirably designed to excite a new interest on the subject through the community； and in this wayand from its tendency to render the art more generally useful； and to elevate and distinguish it to make it to all a matter of more general importance。〃 〃Yours respectfully； 〃M。 A。 ROOT。〃
In our second edition； we hopewith Mr。 Root's permission to lay the whole process before the public； although our artists must bear in mind that Mr。 Root's patent secures to him the exclusive right of its application。
CHAP。 XI。
ON THE PROBABILITY OF PRODUCING COLORED PICTURES BY THE SOLAR RADIATIONS PHOTOGRAPHIC DEVIATIONSLUNAR PICTURESDRUMMOND LIGHT。
Having before noticed the fact that some advances had been made towards taking Daguerreotypes in color； by means of solar rays； and expressed the hope that the day was not far distant when this might be accomplished； I here subjoin Mr。 Hunt's remarks on this subject。
Mr。 Biot； in 1840； speaking of Mr。 Fox Talbot's beautiful calotype pictures； considers as an illusion 〃the hope to reconcile； not only the intensity but the tints of the chemical impressions produced by radiations； with the colors of the object from which these radiations emanated。〃 It is true that three years have passed away； and we have not yet produced colored images； yet I am not inclined to consider the hope as entirely illusive。
It must be remembered that the color of bodies depends entirely upon the arrangement of their molecules。 We have numerous very beautiful experiments in proof of this。 The bi…niodide of mercury is a fine scarlet when precipitated。 If this precipitate is heated between plates of glass； it is converted into crystals of a fine sulphur yellow； which remain of that color if undisturbed； but which becomes very speedily scarlet if touched with any pointed instrument。 This very curious optical phenomena has been investigated by Mr。 Talbot and by Mr。 Warrington。 Perfectly dry sulphate of copper is white；