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• SODA.

tion to many furnaces of the largest dimensions, more especially by Mr. Henry Houlds-worth, of Manchester , who, mounting in the first flue a pyrometrical rod, which actedon an external dial index, succeeded in observing every variation of temperature, pro-duced by varying the introduction of the air-jets into the mass of ignited gases passingout of the furnace. He thereby demonstrated, that 20 per cent, more heat could heeasily obtained from the fuel, when Mr. Williams’s plan was in operation, that whenthe fire was left to burn in the usual way, and. with the production of the usualvolumes of smoke. It is to he hoped, that a law will be enacted in the next session ofparliament for the suppression, or at least abatement, of this nuisance, which so greatlydisfigures and pollutes many parts of London , as well as all our manufacturing towns,while it acts injuriously on animal and vegetable life. Much praise is due to Mr.Williams for his indefatigable and disinterested labors in this difficult enterprise, andfor his forbearance under much unmerited obloquy from narrow-minded prejudice andindocile ignorance.

SOAP. Several contrivances upon this subject have bustled over the patent stagewithin these few years ; such as Mr. Dunn’s for making soap rapidly at a temperatureof 310° Fahr. under high steam pressure, by which many credulous shareholders weregulled into a belief that they would realize by this joint-stock project 200,0001. perannum. The soap so made was merely swelled in size and weight, by being surchargedwith water, so that in a few weeks, the bars of it shrunk, rent, and twisted into mereskeletons; and being in this plight, returned to the company by their customers, causedthat large soap bubble to hurst.

Mr. Sheridan’s silica soap had a somewhat longer career, but is now also nearly con-signed to oblivion. Causticity and abrasiveness were the chief characteristics, resultingfrom the mixture of a strong solution of silicate of soda, or liquor of flints, with soapmade in the common way.

The invention for which Dr. Normandy obtained a patent merits a better fate.When yellow soap is made with the cheaper kinds of fat, it will hardly acquire a suffi-cient degree of firmness or hardness to satisfy the thrifty washerwoman. It melts awaytoo rapidly in the hot water; a defect which-may he well remedied by the introductioninto the soap of a little fused sulphate of soda; and the salt concreting gives the soap adesirable hardness, while it improves its color, and renders it a more economical articlefor the washing-tub. Ina trial recently before the court of common pleas, it was provedthat the soap made according to Dr. Normandy ’s patent was worth fully 2 1. a ton morethan the original soap, without the sulphate of soda.

Mr. Dunn has recently obtained a patent for accelerating the process of soap-making >he promotes the combination of the alkali, fat, and water, by pumping streams ofatmospheric air through the saponaceous materials, while exposed to the usual heat inthe pan. This scheme is said to effect its purpose, and to save much time.

SODA. On the 30th of June, 1838, Messrs. Dyar and Hemmings obtained apatent for manufacturing soda by the decomposition of sea salt with sesqui-carbonate orbicarbonate of ammonia. Equal parts of the ohloride of sodium and sesqui-carbonateare prescribed, being very nearly the equivalent decomposing proportions, and the am-monia salt is recommended to be added in powder to a saturated solution of the sea salt,and the mixture to be stirred and then set aside till the mutual action and decompositionbe effected. Having been employed to examine this process for a gentleman vvh°wished to adopt it upon a manufacturing scale, I obtained the following results : Onmaking the prescribed mixture in the cold, brisk effervescence takes place, becausethe quantity of carbonic acid combined with the ammonia is greater than the resultingsoda can readily absorb, even to form its bicarbonate, and this extrication of gas carriesoff with it more or less ammonia, amounting, in carefully conducted experiments, to no

less than 27 per cent, of the sesqui-carbonate employed; though the magma deposit 1from the mixture was drained in vessels nearly close, and though the ammonia w .* c _adhered to it, as well as that in the drained mother liquors, was recovered by distui -tion in vessels connected with a Woulfe’s apparatus. Moreover, the utmost amountsoda-ash (not pure carbonate) which was obtained, was only 37 - 5 for 100 of sea , s! *used, whereas 90 of carbonate should result from 100 of the sea salt, with the a “° neequivalent dose of sesqui-carbonate of ammonia. This latter salt contains about 0half more carbonic acid than is required by the soda to become a carbonate. A S ^illustration of the loss of ammonia in a similar case is afforded by the decomposition ^chloride of calcium in solution, by adding to it the equivalent dose of pulvo rlammonia carbonate ; viz., 5fi of the former and 59 of the latter. The rapid extric®^^of the carbonic acid on making this mixture, causes such a waste of ammonia,more of the sesqui-carbonate must be afterward introduced, to complete the . jj, s ?sition of the chloride; the stronger the solution of the chloride the greater is tof ammonia.