CHEMISTRY. 



07 





amluing and tasting numerous samples of 

 iiu-at, prepared in many different ways, and 

 preserved, by Herzen's method, for months at 

 tin Mimrner temperature of Florence, declares 

 that no trace of putrefaction could be detected, 

 nor could any indications whatever of change 

 be found with the aid of the microscope. 

 Remnants of a largo quantity of meat, packed 

 without special care in tin cans, that had been 

 carried on two tropical voyages, proved pala- 

 table after a year, and two of his friends sub- 

 sisted upon meat put up in this way for a mouth. 

 A solution of crude boracio acid in water, to 

 which borax has been added, to render it more 

 soluble, is employed in the process. The effect 

 of the solution is also heightened by the addi- 

 tion of salt and saltpetre, which tends to pre- 

 serve the original fresh appearance of the meat. 



Chemical Production of Cellulose. A 

 method of producing cellulose by chemical 

 processes, for paper manufacture, has been pat- 

 ented by Dr. Mitchelich, of Darmstadt, the 

 peculiarity of which is, that theincrusting sub- 

 stance of the wood is not destroyed, but merely 

 separated from the cellulose and made soluble, 

 the original texture being left intact. - Hence, 

 in this process, it is not necessary, as in oth- 

 ers, to divide the wood finely ; a breaking up 

 into pieces like those of domestic fire-wood 

 is sufficient. Jn the process itself, a lime so- 

 lution is used, which is boiled with the wood 

 some 6 hours, at a pressure of 3 atmospheres. 

 After boiling, the incrusting matters are found 

 partly dissolved in the liquid, partly in the 

 pores of the wood, from which latter they can 

 be easily removed by squeezing apparatus. 

 Where a very valuable white paper material is 

 wanted, not in need of bleaching, whitish 

 woods, as free of resin as possible, must be 

 used, such as poplar, willow, or lime. The suc- 

 cess of this process depends much less on the 

 pressure in boiling than on the temperature, 

 which must not rise above 120. The use of 

 oak-wood offers the advantage that the con- 

 tained tannic acid is obtained as a by-product, 

 that may be employed in tanning. 



New Test for Alcohol. While making some 

 experiments on molybdic acid, Dr. E. W. 

 Davy observed that, when a solution of that 

 substance is brought in contact with alcohol, a 

 deep azure-blue color is developed ; and, as the 

 protosulphate of iron and the protochloride of 

 tin, two powerful oxidizing salts, produce a 

 like effect on the solution, there is little 

 doubt that it is due to the deoxidizing action 

 of alcohol. This reaction of alcohol on the 

 molybdic solution is extremely sensitive; thus, 

 if one part by volume of commercial rectified 

 spirits be mixed with 100 parts of distilled 

 water, and one drop of this mixture brought 

 in contact with it, a deep-blue coloration is at 

 once developed. 



Thouh small quantities of spirit, even when con- 

 siderably diluted with water, will produce with the 

 molybdic solution the blue reaction without the as- 

 istance of any external heat, still, where very mi- 

 nute quantities, diluted with such large proportions 

 VOL. xvi. 1 A 



of water as those just stated, are to be detected, it 

 i.s necessary, for the success of the experiment, that 

 the reaction should be assisted by a gentle heat, and 

 also that too great a dilution of the test-solution 

 with the liquid under examination should be avoid- 

 ed, as the blue coloration will not be developed if 

 water be in excess ; and, even after it has been pro- 

 duced, the addition of a certain proportion of that 

 substance quickly causes its disappearance. Such 

 being the case, tLe best way of employing the test 

 is to place three or four drops of the molybdic solu- 

 tion in a sum!!, white, porcelain capsule, and, having 

 heated them slightly, allow one or two drops of the 

 liquid to be examined to glide or fall gently on the 

 acid solution, when there will be developed, either 

 immediately or after a few moments, the blue color- 

 ation. And, where the alcohol is very largely diluted 

 with water, it is better to continue the gentle heating 

 of the test solution for some time, to concentrate it 

 or expel as much water from it as possible, before 

 adding the liquid to be tested j for. in this way, the 

 author has succeeded in detecting the spirit in mixt- 

 ures BO dilute as to give no blue reaction when 

 added immediately to the test solution on its being 

 simply warmed. As regards the application of heat, 

 the temperature of the acid solution must not be 

 raised too high, for, if it be heated till the acid 

 evolves its dense vapors, or begins to boil, the solu- 

 tion will of itself alone, from its partial decomposi- 

 tion, develop more or less blue coloration, which will 

 become more perceptible on its cooling. But such 

 an occurrence can be easily avoided by employing a 

 water-bath as the heating agent. 



But the coloration produced in the reaction stated 

 disappears after a variable interval of exposure to 

 the air a circumstance which is due to the absorp- 

 tion of moisture from the atmosphere, and not to the 

 reoxidation of the molybdenum compound, as might 

 have been supposed. 



The reaction is not peculiar to ordinary or ethylic 

 alcohol, but is more or less readily developed by 

 others at least the author found it to be so in the 

 case of methylic, propylic, butylic, and amylic alco- 

 hols', those being the only ones he had for his ex- 

 periments. But it is more than probable that some 

 at least of the other alcohols may act in a similar 

 manner : however, the reaction is much more rapid 

 and striking in the case of ethylic than in that of 

 any of the other alcohols mentioned. 



This test is of especial value for determining 

 the purity of chloroform and chloral hydrate, 

 one of the common impurities of the former 

 being ethylic alcohol, and of the latter chloral 

 alcoholate. 



Extraction of Iodine from Seaweed. Mr. 

 Thowald Schmidt, of Aalborg, Jutland, has 

 devised the following new method of obtain- 

 ing iodine, potash-salts, and other commercial 

 products from seaweed : After the seaweed is 

 dried and burned, a concentrated solution of 

 the ash is added to the liquor containing chlo- 

 rides of sodium and calcium, left after the 

 ammonia has been recovered in the ammonia- 

 soda process by boiling wHh lime. The sul- 

 phates of potnsh, soda, and magnesia con- 

 tained in the ash of the seaweed are there- 

 by decomposed, and hydrated sulphate of lime 

 and hydrated magnesia are precipitated in a 

 form which may be available for paper-making 

 as " pearl-hardening." The last traces of sul- 

 phates are got rid of by adding a small quan- 

 tity of solution of chloride of barium. To the 

 clear solution nitrate of lead is now added un- 

 til all the iodine is precipitated as iodide of 



