Starch is made from wheat flour in a like way. The gluten may be recovered for use, by saturating the alkaline solu tion with sulphuric acid, washing and drying the precipitate.
In 1841, Mr. W. T. Berger obtained a patent for manufacturing starch by the agency of an alkaline salt upon rice. He prefers the earbonat es of potash and soda.
Mr. James Colman, by his patent in vention of December, 1841, makes starch from ground maize or Indian corn, by the agency either of the ordinary process of steeping and fermenting, or of caustic or carbonated alkaline leys. He also pro poses to employ dilute muriatic 'acid to purify the starchy matter from gluten, &c. Mr. Colman has taken out a patent re cently for an improved process : the sub joined is the plan given in his specifica tion. Take one ton of rice, either whole or broken, with or without the husk, and submit it to the action of caustic alkaline ley, in the manner at present performed, using soda in preference to potash, as affording a less deliquescent product. Wash the rice so prepared, and then pass it through the grinding or levigating mills in time usual manner, so as to reduce the starchy matter to a pulp, in a fine state of division. The washed pulp so obtained is next to be placed in a churn, together vrith 40 gallons of a solution pre pared in the following manner :—Take N lbs. of borax, and dissolve it in such a quantity of hot or cold water as will suf flee to form a cold saturated solution ; for which purpose about 20 parts of water are requisite for I part of bong; pour 40 gallons of clear solution of borax thus made on a bushel of unslacked lime, placed in any suitable vessel; stir the mixture, and add to it enough water to make up the quantity used to 50 gallons. Allow the undissolved portions in the mixture to precipitate, draw off the clear supernatant solution, and place it in the churn with the starch pulp, prepared in the manner before mentioned. The con tents of the churn are next to be sub jected to agitation for two or three hours, so as to bring each particle of the starchy matter in communication with the alka line solution. When the desired effect has been produced, the mixture is to be run from the churn into the separating vessel, and about as much water as the churn will bold added to it (dimensions or capacity of churn not given); the whole is to be now well stirred, and the starch washed, boxed, and dried in the usual way. Instead of borax and lime, as above mentioned, the same quantity of solution of borax alone may be used or a solution of bitartrate of potash and lime, or a solution of hitartrate of potash alone may be employed. In either case,
the process is to be conducted as above described. In the case of any other far inaceous or leguminous substance than rice being employed, the material used must be reduced to a fine pulpy state, as in the case of rice, proceeding as above directed.
For the manufacture of starch from the see POTATO STARCH. 111C111111 corn yields, by analysis, over 70 per cent. of starch. The manutacture of starch from corn is an extensive operation in some districts of this country.
There arc several other varieties of starch, which are called differently ac cording to the sources whence derived, as sago from tapioca, tons le mois, arrow-root, farina, &c.
The characters of the different varie ties of starch can be learned only from microscopic observation ; by which means also their sophistication or ad mixture may be readily ascertained.
Starch, from whatever source obtained, is a white soft powder, which feels crispy, like flowers of sulphur, when pressed be tween the fingers ; it is destitute of taste and smell, unchangeable in the atmos phere, and has a specific gravity of 1•53. We have already described the particles as spheroids enclosed in a membrane. The potato contains some of the largest, and the millet the smallest. Potato starch consists of truncated ovoids, varying in size from 1-800th to of an inch ; arrow-root, of ovoids varying in size from to of an inch ; flour starch, of insulated globules about 1-1000th of an inch ; cassava, of similar globules assembled in groups. These measurements have been made with a good achromatic microscope, and a divided glass-slip micrometer of Tully.
For the saccharine changes which starch undergoes by the action of diastase, 8Ce FERMENTATION.
Lichenint, a species of starch obtained from Iceland moss (Cetraria itiandica), as well as in:Idiot, from elecampane (In Ida Nelenieno), are rather objects of chemical curiosity, than of manufacture.
There is a kind of starch made in order to be converted into gum for the calico printer. This conversion having been first made upon agreat scale in Eng land, has occasioned the product to be called British gum.
A delicate and ready test of the pre sence of starch exists in iodine, with which the starch forms a deep blue color, or, if in the liquid form, a solution color ed blue. This color disappears on boil ing, re-appears on cooling, and is destroy ed by chlorine and sulphurettod hydro gen. To produce the color, the starch should be boiled, and the iodine should be free—that is, not united to any other substance.