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Lithography in imitation of mezzotint
Removing ,t?cld from Paper.--Imilcttion of Mezzotint. 203 large stones are used. This has hitherto been a great obstacle in the progress of the lithographic art. This ridge had been reduced~ and practice had taught a method of concealing, in part~ the defects necessarily attendant upon the use of rollers with seams; but the inconvenience and many defects still remained to be remedied. M. Tudor, incited by an appeal of the Society for tile Encouragement of National Industry~ conceived tile idea of making rollers of round plates of different substances cut with a punch~ then threaded together on a cylinder of wood, pressed |orcibly one against tile other, and polished or trimmed. I[e has tried in this way chamois leathe,', calico, aml calf skin. This last material answered best~ anti furnished rollers which were soft, without seams, and which distributed tile ink uniformly. M. de Lasteyrie~ a competent judge in these matters, observes that tile ordinary (seamed) rollers are very quickly worn out, while those of M. T. will not be exposed to the operation of' the same causes of wear and teat', and will, therefore~ greatly outlast tile others. The new rollers are rather higher priced than the common ones, but it is coniidently expected that their continued manufacture will admit of a reduction in the price. M. Tudor has received a prize of 500 francs (.$100) for the ingenuity displayed in his invention.
[ Mdmorial JEn~jclopddique, ~'e.
Method of removing .~cidfrom the papers used in Lithographic Printing. Most of the paper used ill copperplate and lithographic printing has an acid reaction, due, doubtless, to the processes of whitening, or to the alum used in its manufacture. This acid soon injures the texture of tile lithographic stones, and after, at tnost~ thirty, impressions have been taken, the stone ~reaa'e8, to use the expressmn of the workmen, and the impressions are imperlect. M. Joumar remedies this greasing of the stone, in a wwy simple way ; he passes the paper intended to receive the impression, through weak lime water, which neutralizes tile acidity; he leaves it through the night thus wet and ~natted, and on the following morning eitller dries it or takes off tile superabundant moisture, keeping that degree of softness which the printing requires. 'File author of this simple and easy method of re,uoving tile acid from litilographic papers, ltas received a medal of the value of ~00 ti'ancs, (S40.) [Ibid.
Lithography in imitation of Mezzotint. Various attempts have been made to imitate the style of mezzotinto engraving by lithography. One of the methods tried was by tampiny;. This process had given some beautiful results, but tile n,ellowness of the tints could notbe obtained. Be~itles, in sketching
284
Cure f o r Pai~ter's Colic.
on the stones and removing the superabundant ink with the scraper, for tile clear parts, the grain of tile stone was destroyed~ anti when the stone was heated, for the purpose of fixing tile sketch upon it, a few engravings with tarnished and gluey, tints were. • all. that couldbe obtained. M. Tudor proposes another process m which the scraper is not used. He lays tile lithographic ink on the stone with care~ makes it penetrate into the grain by means of an instrument of horn, lhen with a point of ivory, or, in preference, with a small utensil composed of very fine and pointed threads of steel, he takes from the bottom of the grain as much of the crayon as he thinks necessary to produce the desired tints. This process, put in practice by able workmen, has produced designs rivalling in every particular engravings.which have come from the hands of the most celebrated engravers m mezzotint. The artist, while transferring to the stone the conceptions of his genius, has every desirable freedom, is not embar. rassed with any mechanical operation, and the process is very rapidly executed. In some trials, made in presence of" the Society for the En. couragement of National Industry, the 800th impression was as beautiful as the first. M. Tudot has received for this application agold medal of the value of ~000 ti'ancs, ($400.)
[Bulletin of Soc. for L'ncour. of Nat. Ind., ~,c. 20 Dec. and Ibid.
Curefor Painter's Colic. Plumbers, manufacturers of white lead~ painters, printers, &e. and~ generally, all persons exposed to the action of lead, are subject to this colic. Many remedies have been employed in this complaint; the one most generally adopted, and which has been attended with constant success, consists in administering emetics and purgatives. This method is obviously troublesome, and is besides expensive. M. Gendrin has communicated to the Academy of Sciences, a new remedy, viz. ttle acid sulphate of alumina and potassa, or common alum, dissolved in a sufficient quantity of water, and given in a dose of from one to three grains a day. This mode of treatment had been before recommended by Adair, Miehaelis, &c. and is now in general use at the hospital of St. Anthon,:. The alum thus taken cures the malady compietelv in the space of from three to five (lays, without in the least weakening the organs of digestion. Its use in a dose of from one to one and a half grains,* is stitl more beneficial at the commencement of the attack; twelve or fifteen hours are then sufficient to remove all the symptoms. M. G. considers the efficacy of the alum to be probabl~ due to the sulnhuric acid, which enters into ~ts composition. In fh'ct, a sulphuric le'monade, made of one gros! to lx of acid, in twelve litres.+ of water, given to persons sufferi% under the painter's colic, has produced a complete and speedy cure. The sulphuric acid thus used with water as a lemonade, is as well as the alum, a sure preventive if taken on the first symptoms of the * French, 2-3ds of a grain troy. t 54. troy grains. ~ 25~ pints.
[ Mdmorial JEn~jclopddique, ~'e.
Method of removing .~cidfrom the papers used in Lithographic Printing. Most of the paper used ill copperplate and lithographic printing has an acid reaction, due, doubtless, to the processes of whitening, or to the alum used in its manufacture. This acid soon injures the texture of tile lithographic stones, and after, at tnost~ thirty, impressions have been taken, the stone ~reaa'e8, to use the expressmn of the workmen, and the impressions are imperlect. M. Joumar remedies this greasing of the stone, in a wwy simple way ; he passes the paper intended to receive the impression, through weak lime water, which neutralizes tile acidity; he leaves it through the night thus wet and ~natted, and on the following morning eitller dries it or takes off tile superabundant moisture, keeping that degree of softness which the printing requires. 'File author of this simple and easy method of re,uoving tile acid from litilographic papers, ltas received a medal of the value of ~00 ti'ancs, (S40.) [Ibid.
Lithography in imitation of Mezzotint. Various attempts have been made to imitate the style of mezzotinto engraving by lithography. One of the methods tried was by tampiny;. This process had given some beautiful results, but tile n,ellowness of the tints could notbe obtained. Be~itles, in sketching
284
Cure f o r Pai~ter's Colic.
on the stones and removing the superabundant ink with the scraper, for tile clear parts, the grain of tile stone was destroyed~ anti when the stone was heated, for the purpose of fixing tile sketch upon it, a few engravings with tarnished and gluey, tints were. • all. that couldbe obtained. M. Tudor proposes another process m which the scraper is not used. He lays tile lithographic ink on the stone with care~ makes it penetrate into the grain by means of an instrument of horn, lhen with a point of ivory, or, in preference, with a small utensil composed of very fine and pointed threads of steel, he takes from the bottom of the grain as much of the crayon as he thinks necessary to produce the desired tints. This process, put in practice by able workmen, has produced designs rivalling in every particular engravings.which have come from the hands of the most celebrated engravers m mezzotint. The artist, while transferring to the stone the conceptions of his genius, has every desirable freedom, is not embar. rassed with any mechanical operation, and the process is very rapidly executed. In some trials, made in presence of" the Society for the En. couragement of National Industry, the 800th impression was as beautiful as the first. M. Tudot has received for this application agold medal of the value of ~000 ti'ancs, ($400.)
[Bulletin of Soc. for L'ncour. of Nat. Ind., ~,c. 20 Dec. and Ibid.
Curefor Painter's Colic. Plumbers, manufacturers of white lead~ painters, printers, &e. and~ generally, all persons exposed to the action of lead, are subject to this colic. Many remedies have been employed in this complaint; the one most generally adopted, and which has been attended with constant success, consists in administering emetics and purgatives. This method is obviously troublesome, and is besides expensive. M. Gendrin has communicated to the Academy of Sciences, a new remedy, viz. ttle acid sulphate of alumina and potassa, or common alum, dissolved in a sufficient quantity of water, and given in a dose of from one to three grains a day. This mode of treatment had been before recommended by Adair, Miehaelis, &c. and is now in general use at the hospital of St. Anthon,:. The alum thus taken cures the malady compietelv in the space of from three to five (lays, without in the least weakening the organs of digestion. Its use in a dose of from one to one and a half grains,* is stitl more beneficial at the commencement of the attack; twelve or fifteen hours are then sufficient to remove all the symptoms. M. G. considers the efficacy of the alum to be probabl~ due to the sulnhuric acid, which enters into ~ts composition. In fh'ct, a sulphuric le'monade, made of one gros! to lx of acid, in twelve litres.+ of water, given to persons sufferi% under the painter's colic, has produced a complete and speedy cure. The sulphuric acid thus used with water as a lemonade, is as well as the alum, a sure preventive if taken on the first symptoms of the * French, 2-3ds of a grain troy. t 54. troy grains. ~ 25~ pints.