MECHANICS AND USEFUL ARTS. 75 



tion of a greater or less quantity of one or the other of these salts. 

 The precipitate, after being- washed and dried, is redissolved in a sic- 

 cative essence, or a mixture of good varnish of linseed oil and wax ; 

 and with this solution the figures (having been previously heated) are 

 coated ; on drying, they will be found to possess the color mentioned 

 above. Perhaps a better result is obtained by employing a solution 

 of the salt of iron only, instead of the mixed solution of the sulphates. 



PATENT FOR A DAGUERREOTYPE CASE. 



AN invention of a lady, consisting of a conical glass case, black- 

 ened on the upper half of its inner surface, and ground on its lower 

 half to admit the light necessary for viewing the picture, which is se- 

 cured in the larger end of the case, the smaller end being provided 

 with a magnifying lens, through which the picture is to be examined. 

 In the ordinary examination of these pictures, every one must have 

 observed the difficulty of getting a proper light. The specular reflec- 

 tion of the plate interferes with the view, and it is necessary to admit 

 the light to the plate laterally, and hold over it some dark or absorb- 

 ing surfaces. Persons wearing dark dresses can generally obtain a 

 good position, without much trouble. This inconvenience is obviated 

 by the invention, and as the picture will bear magnifying with advan- 

 tage, the lens comes in opportunely for this purpose, as well as that of 

 closing entirely the glass case, and preserving the picture from dust 

 and exposure to the air. Patent Office Report, 1849. 



IMPROVEMENTS IN THE MANUFACTURE OF STARCH. 



A PATENT has been granted during the year, in England, for im- 

 provements in effecting the separation of starch from other substances 

 with which it is combined in farinaceous and leguminous materials, by 

 a more expeditious process, and by the use of cheaper agents, than are 

 commonly employed. The substance of the specification is as fol- 

 lows : We take whole or broken grains of rice, with or without the 

 husk, or rice flour, and place in a shallow, or other convenient vessel. 

 We then pour in a solution of lime and common salt, sufficient to 

 cover the whole of the rice, about 26 gallons of the solution to about 

 112 pounds of rice. The solution is made by mixing slacked lime, 

 salt, and \vater, in the proportion of about 100 pounds of lime and 30 

 of salt to 500 gallons of water. The solution is allowed to settle, and 

 the clear liquor only made use of. We let the rice remain thus sub- 

 merged for six hours, stirring it well every half-hour. The liquor is 

 then drawn off by suitable taps, and a fresh solution added, which, after 

 standing six hours, is also drawn off. The rice is then ready to be 

 ground, which is effected in the ordinary way. The ground rice is 

 then transferred to a suitable vessel, covered with a similar solution, 

 and well stirred for two or three hours. From this vessel the rice is 

 removed to a separating vessel, where it is left to stand for six hours. 

 In this time the starch separates from the gluten and falls to the bot- 

 tom of the vessel, while the gluten floats upon the top liquor. The 



