112 



CHEMISTRY. 



organic matter present in the water thus deter- 

 mined. 



While the method of testing sugar for the 

 presence of starch glucose by the optical sac- 

 charometer is satisfactory, it can be applied 

 only by the very few persons who have such an 

 instrument. Mr. P. Casamajor has described 

 a process which can he applied by using such 

 means as are at the command of every one, 

 and is effective for the detection of adultera- 

 tion with either anhydrous or hydrated glu- 

 cose, as follows: Take two beaker-glasses, or 

 two teacups ; in one put a quantity of the sus- 

 pected sugar, and in the other put about the 

 same quantity of a sugar known to be refined 

 sugar, free from adulteration. Add, cautiously 

 and gradually, a quantity of water to each 

 sugar sufficient to make each equally and de- 

 cidedly moist, and stir the sugar to mix it well 

 and get it uniformly wet. Then place both 

 cups in hot water at any temperature be- 

 tween 50 and 100 0. In about ten minutes 

 the pure sugar will appear more moist than 

 when cold, while the other sugar, if it con- 

 tains a sufficient amount of starch-glucose, will 

 have sunk into a pasty, sticky mas?, analogous 

 to the fill-mass of sugar-refiners. The appli- 

 cation of heat is not indispensable, as a differ- 

 ence may be obtained by allowing the two su- 

 gars to stand several hours after being moist- 

 ened, but with heat the effect is immediate, 

 and is much more marked. If the two samples 

 of sugar are allowed to stand in the cups after 

 they have cooled down, the pure sugar will 

 look drier on becoming cold, while the adul- 

 terated sugar will continue in the state of a 

 pasty, sticky mass. This test is founded on the 

 property possessed by cane-sugar of forming 

 viscous, uncrystallizable compounds, of which 

 molasses is an example, when mixed with many 

 organic or inorganic compounds, among which 

 are anhydrous and hydrated glucose. As long 

 as a mixture of cane-sugar and starch-glucose 

 is sufficiently dry, it may look fairly enough, 

 as the elements which form molasses are kept 

 from combining by want of water. Hence 

 adulterators are careful to dry their sugars be- 

 fore mixing with glucose. Indeed, one char- 

 acteristic of adulterated sugars is, that they are 

 drier than refined sugars of the same grade, 

 which are known as coffee-sugars, and are 

 always sold moist. 



Peter Claesson proposes a new method for 

 determining sulphur in organic substances by 

 effecting the complete oxidation of the sub- 

 stance in a current of oxygen and nitric oxide 

 i. e., nitrogen tetroxide gas. A combustion- 

 tube somewhat longer than the furnace is 

 drawn out at one end and bent at a right an- 

 gle. Next to the bend is placed a roll of plat- 

 inum gauze; beyond this a boat containing 

 fuming nitric acid ; beyond which follow a sec- 

 ond and a third roll of platinum gauze, and 

 beyond this the sulphur-boat and a fourth roll 

 of platinum gauze. The bent end of the tube 

 dips into water in a small flask, and the other 



end is closed with a stopper admitting the con- 

 necting tubes to the oxygen and nitric oxide 

 supplies. After filling the tube with the mixed 

 gases the platinum roll on either side of the 

 nitric-acid boat is heated to low redness, then 

 the boat farthest from the substance. The 

 tube is then heated. The color of the tube 

 between the two boats serves as an indicator ; 

 if the red color disappears, the combustion 

 must go more slowly. The nitric acid in the 

 boat acts as a reserve ; the hot gases in pass- 

 ing over it always take up enough oxygen 

 compounds to complete the oxidation of any 

 unburned particles. At the end of the com- 

 bustion the heating is extended forward until 

 all the nitric acid and the sulphuric acid formed 

 in the reaction have distilled over into the 

 flask. After cooling, the contents of the flask 

 and the washings of the tube are evaporated 

 to dryness, and after dilution with water the 

 sulphuric acid is determined as barium sul- 

 phate. 



C. Bohmer has described a new method of 

 estimating nitric- oxide gas obtained by the re- 

 duction of nitric acid. It is hased on the fact, 

 which the author had shown in an earlier 

 paper, that chromic acid is an excellent ab- 

 sorbent for nitric oxide. The nitrate or nitric 

 acid is decomposed in the usual way, and the 

 resulting gas, after being dried by calcium 

 chloride, is absorbed in a Liebig's potash-bulb 

 containing chromic acid, and the nitric oxide 

 is determined by the increase in weight. 



\V. Ilalberstadt has proposed a new method 

 for the separation of vanadic acid from met- 

 als, which is based on the fact that, when a 

 mixture of the acid and metals is heated with 

 ammonium oxalate and acetic acid, the metals 

 are precipitated as oxalates, while the acid 

 sought for remains in solution. The hydro- 

 chloric-acid solution of vanadic acid is evapo- 

 rated to dryness, the residue is heated with a 

 solution of ammonium oxalate in water, and a 

 few drops of strong acetic acid are added till all 

 has dissolved. The liquid is poured into a beak- 

 er and heated over a free flame, while acetic acid 

 is added drop by drop not too rapidly, for 

 then the precipitate is difficult to wash until 

 the precipitate ceases to form. After filtering 

 off the precipitate and washing with a mixture 

 of equal parts of strong acetic acid, alcohol, 

 and water, the filtrate is evaporated to dryness 

 in a weighed platinum dish, and the residue is 

 heated slowly to expel volatile ammonium 

 salts, and then the remaining vanadium oxide 

 is converted into vanadic acid by heating in a 

 current of oxygen. The method gives good 

 results in the presence of barium, calcium, 

 zinc, or lead, but not with cobalt, nickel, man- 

 ganese, magnesium, bismuth, copper, or cad- 

 mium. 



Mollenda determines, volumetrically, the 

 phosphoric acid in superphosphates by finding 

 the amount of a standard solution of sodium 

 carbonate necessary to neutralize the acid 

 phosphate of calcium, which forms the solu- 



