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i^'' -. Chemistry and Physics. 117 



tion of codein absorbs cyanogen with avidity and yields a new base 

 dicyanocodein, CioH^iNsOg or 2C2N, CsGHsiNOe. Distilled with 

 four or five limes its weight of soda-lime or potash-lime, codein yields 

 several organic bases among which Anderson succeeded in identifying 

 melhylamine and propylamin, CeHgN. — Amu der Cliemie nnd Pliar- 

 made, March, 1851, Ixxvii, 341. 



8. Acetic Acid from Sea-weeds. — Stenhouse has found acetic acid 

 in considerable quantity among the products of the fermenlation of va- 

 rious species of sea-weed. Fucus nodosus yielded r45 per cent., 

 Fucus vesiculosus 1-15 per cent, of the weight of the moist plant. 



W. G. 



9. Neio Test for the Nitrites and Nitrates; by Geokge C. Schaef- 

 PER, Prof, of Chem. and Nat. Phil., Centre Coll., Danville, Ky., (Proc. 

 Amer. Assoc, 4ih meeting at New Haven, 1851, p. 403.)— Chemistry 

 has hitherto furnished no distinctive test for the nitrites, when present 

 in small quantities. From the supposed unfrequent occurrence of these 

 salts, the want of such a test has never been felt. 



For several years I have been encraiied in a research which has led 

 nie to believe that the nitrites are of fur more frequent occurrence than 

 IS commonly supposed, and that they have been mistaken for nitrates, 

 as the usual process, with pure sulphuric acid and protosulphate of Iron, 

 \vill give the same reaction with both classes of salts. In order to 

 settle the question, it was necessary to find a distinctive lest, which should 

 avoid all risk of confusion, I first tried acetic acid, which, as is well 

 ^novvu, does not act upon the nitrates, while it decomposes nitrites, 

 l^y substituting this acid for the sulphuric in the usual , process, I suc- 

 ceeded perfectly. The test seemed even more delicate than that for 

 the nitrates, and was more elegant in its operation. 



fetill the following difficulties were to be encountered. The slightest 

 quannty of peroxyd in the sulphate gave a color with acetic acid, and 

 injured the delicacy of the test. Moreover, the nitrites are generally 

 either destroyed or converted into nitrates, with such readiness, that it 

 would be almost impossible to concentrate their solutions. 



At last I was led to the following process, which leaves nothing to 



e desired. To the solution supposed to contain a nitrite, add one or 



Wo drops of solution of yellow prussiate of potash — there should not 



e enough to give a perceptible tinge to th* liquid. A few drops of 



acetic acid are then to be added, and immediately, or in a few minutes, 



according to the quantity of nitrite present, the liquid assumes a rich 

 yellow tint, ^ -^ t ' 1 



As the re-agents used give nearly the same color, spontaneously, 



^ ter some time, even in pure water, it is belter, when testing for minute 



quantities, to use two similar vessels, one containing pure water, and 



e other the liquid under examination, to both of which the re-agents 



*^e to be added in precisely equal quantities. The vessels should be 



^^"Jl'y ^^posed to the light, with a sheet of white paper behind them. ' 



J^ah these precautions, I have found this test astonishingly delicate, 



n tact ranking with those for iron, iodine, &c. Using fused nitre, I 



n^ve detected the presence of one pt. in 617,000 pts. of water ; a by- 



ander wholly ignorant of the nature of the operation, pronouncing as 



o the color. Yet this salt contained about one-half its weight of un- 



^ecomposed nitrate. 



