110 



CHEMISTRY. 



tliis purpose a 4 ft. length of 75 Ibs. double-headed 

 rail was laid on its side, being supported at each end 

 at a height of 3 in. from the ground. A charge of 

 3 Ib. 3 oz. of the compound was placed in a lump on 

 the centre of the rail, and tamped with paper, three 

 old sleepers being placed on the tamping, and fired 

 with a percussion fuse. A startling report ensued, 

 the fragments of the sleepers being sent in all direc- 

 tions, and on examination the rail was found much 

 bent, and with one head cut through, and 11 in. of 

 the web blown away in the centre. 



Delicate Test for Nitric Acid. The employ- 

 ment of sulphate of aniline as a reagent to de- 

 tect with accuracy the least trace of nitric acid, 

 is recorded in the Scientific American. The 

 modus operandi is as follows : Place in a 

 watch-glass about 1 cubic centimetre of pure 

 and concentrated sulphuric acid at 1.84 ; then 

 pour, drop by drop, half a cubic centimetre 

 of a solution of sulphate of aniline, prepared 

 by mixing 10 drops of commercial aniline with 

 50 cubic centimetres of diluted sulphuric acid. 

 A glass rod is dipped in the liquid to be tested, 

 and then introduced in the watch-glass and 

 stirred in a circular way, the experimenter 

 from time to time blowing slowly on the 

 agitated liquid. If it contains traces of nitric 

 acid, circular lines of a deep red are soon vis- 

 ible, coloring the whole liquid to a pink. On 

 adding a very small quantity of nitric acid to 

 the liquid, it becomes of a carmine color. This 

 simple process can be applied to the detection 

 of nitric acid in the commercial sulphuric acid. 

 Hypoazotic or hyponitric acid produces the 

 same reaction ; moreover, when any traces of 

 hyponitric acid are detected, the distinction can 

 easily be made by the use of starch and iodide 

 of potassium, acidulated by sulphuric acid. 



The Spectroscope in Chemical Analysis. The 

 editor of the Boston Journal of Chemistry 

 gives a chapter from his experience in chem- 

 ical spectroscopy, concerning which less is 

 generally known than about the use of the 

 spectroscope in astronomical researches. He 

 says: 



We have tried several forms of instruments, with 

 prisms varying in number from one of flint glass to 

 six of bisulphide of carbon, and, as the result of these 

 trials we have concluded that an instrument fur- 

 nished with good telescopes and a single flint-glass 

 prism is all that is necessary for chemical use. A 

 piece of apparatus that requires much adjustment or 

 delicate manipulation is altogether out of place in the 

 laboratory. 



A common fault with the ordinary spectroscope is, 

 that they are made too small in all their parts. We 

 should prefer for our own use an instrument which 

 had telescopes of two inches aperture, although those 

 of one inch aperture do very good work. But with 

 the large instrument we have been enabled to detect 

 potassium and rubidium in substances in which our 

 small instrument did not show a trace. 



The scales with which almost all spectroscopes are 

 furnished are of but little use except to the beginner, 

 and we have even then found them to be of a positive 

 disadvantage. The eye may soon be educated to 

 know the relative places and the colors of the lines 

 given by the various elements. It is much less liable 

 to eiT than when an arbitrary scale is used that may 

 become displaced. The sodium line is always pres- 

 ent, and serves as a standard of reference. The 

 scales on no two instruments that we have ever seen 



were precisely alike, and therefore, in referring to 

 scale numbers, it is always necessary to reduce them 

 to some known standard. 



Candy Adulterations. Mr. Endemann, as- 

 sistant chemist of the New York Health De- 

 partment, has examined a great variety of 

 candies collected from various dealers by the 

 sanitary inspectors. The following is the sub- 

 stance of his report : 



^Inorganic adulterations were detected in 

 only two cases, in both cases in lozenges, to 

 the extent of three and six per cent. In one 

 establishment visited, a white powder was ob- 

 tained, which proved to be gypsum, sulphate 

 of lime. 



" Coloring-Matters. Eeds were either car- 

 mine or aniline red ; both harmless. 



"Blues were either ultramarine or Prussian 

 blue ; both harmless. 



" Yellows were either saffron, chromate of 

 lime, chromate of baryta, chromate of lead, 

 gamboge, or yellow vegetable colors precipi- 

 tated by alum and chalk. 



" Of ten samples examined, five were col- 

 ored with chromate of lead and one with gam- 

 boge, both of which are poisonous. 



u Greens were found to be harmless. 



" Flavors. Oil of peppermint is often adul- 

 terated with oil of turpentine. The other 

 flavors "are generally artificial ethers, as, for 

 example, butyric ether. Many of these are 

 considered injurious. 



" Substitutes for Sugar and Gum-Arabic. 

 Glucose, starch-sugar, is common in some kinds 

 of candy. Starch is extensively used as a sub- 

 stitute for the more expensive gum-arabic. 

 Both of these substances are harmless. 



"In conclusion, the public is cautioned 

 against highly-colored yellow, orange, and 

 green candies, and against highly-flavored can- 

 dies." 



Utilizing Gas-Lime. Lime spoiled in the 

 purification of gas has long been regarded as a 

 waste product, and the expense and trouble 

 of its removal drove the London gas compa- 

 nies to use ferric hydrates in its stead. This 

 residuum is now employed in making " Prideux 

 cement," for protecting floors and roofs from 

 rain ; also for paving-stones, with a prepa- 

 ration of broken flag, and as a material for 

 hearths and mantel -pieces. The cement 

 " sets " in about twelve hours. The London 

 Builder says of its composition : 



It is not a Portland or a Roman cement, although 

 some hydraulic characters are very distinct. It does 

 not set so quickly, but allows more time for finishing 

 up the faces of moulded work. It is far from common 

 mortar, for without any sand it can be formed into 

 blocks, which set hard throughout. A piece of a 

 mantel-piece which had been made some six months, 

 gave the following results upon analysis : 



Carbonate of lime 69.08 



Sulphate of lime (hydra ted) 22.63 



Hydrate of lime 1.36 



Sulphide of calcium trace 



Insoluble matter 6.50 



Alumina and oxide of iron 45 



It is obvious, from the above, that the setting must 

 at first be due to the combination of water with the 



