112 



CHEMISTRY. 



from the Chemical News, are the results of 

 some recent researches by M. Mercaclante con- 

 cerning the chemical changes that take place 

 in fruits during the processes of growth and 

 ripening : 



In the first period of their existence fruits behave 

 like leaves, decomposing carbonic acid under the 

 influence of the sun's rays, and giving out oxygen. 

 In the second period they absorb oxygen and give 

 off carbonic acid. In the third the sugar which they 

 contain passes into the alcoholic fermentation. On 

 the 20th of May the author began to determine the 

 acidity and the sugar in green plums. The acid- 

 ity and the sugar were found to increase very 

 sensibly. The branches contained no other acid 

 than the malic, accompanied by pectic and gummy 

 matters. The fruit behaved exactly like leaves with 

 respect to the air, giving out oxygen by day and ab- 

 sorbing carbonic acid. Continuing his analyses he 

 found that the maximum acidity was when the fruit 

 began to give off carbonic acid by day. It contained 

 then 2.76 of malic acid in 100 of pulp. The sugar is 

 derived from the prolonged action of the malic acid 

 upon the gummy matter which in the earlier analyses 

 amounted to 6.21 per cent, of pulp, but in the second 

 to 3.34, at which quantity it remained nearly con- 

 stant, 3.27 per cent, of gum being still found on 

 July 18th. The successive changes in the amounts 

 of sugar and malic acid are shown in the following 

 table : 



The acids themselves thus appear to be trans- 

 formed into sugar. 



Detection of Arsenic in Organic Matter. 

 Dr. Arm and G-autier proposes a new method 

 for separating arsenic from animal matters, 

 and for detecting its presence. By combining 

 the sulphuric acid and nitric acid" processes he 

 has obtained very satisfactory results, both as 

 regards the rapidity of the operation and the 

 exactness of the determination. He first treats 

 the matter supposed to contain arsenic with 

 nitric acid, then with sulphuric acid, and again 

 with nitric acid. By the first operation the 

 organic substances are disaggregated ; by the 

 second they are destroyed very rapidly; and 

 by the third, the addition of more nitric acid, 

 the last traces of organic matter are elimi- 

 nated. The solution is then evaporated and 

 the residue heated to incipient carbonization. 

 The matter thus obtained is powdered, and ex- 

 hausted in a capsule with boiling water, the 

 filtrate is treated with a few drops of sodium 

 bisulphite, and the arsenic is then thrown down 

 as sulphide by a prolonged current of sulphu- 

 retted hydrogen. This sulphide is converted 

 into arsenic acid by ordinary methods and then 

 submitted to Marsh's apparatus. 



Detection of Artificially -Colored Wine. 



The following simple tests for detecting arti- 

 ficially-colored red wine are given in the Amer- 

 ican Chemist, from Reimann's Farberzeitung : 



Dilute the wine with twenty times its volume of 

 water. On addition of plumbic acetate solution 



(1 : 10) the color of genuine wine will then disap- 

 pear, the solution becomes turbid, and, on heating, 

 small silver-gray flocks with a reddish cast separate 

 out. Artificially-colored wine, under these circum- 

 stances, gives large curdy flocks of a dark-violet 

 color. Solution of cupric sulphate (1 : 10) with un- 

 adulterated wine destroys the color without causing 

 turbidity. With artificial wine the color becomes 

 violet-blue, and a slight turbidity appears. Baryta 

 water (1 : 10) destroys almost completely the color 

 of unadulterated wine, showing at the same time a 

 trifling turbidity. With colored wines the solution 

 becomes violet-blue to bluish-green, and at the same 

 time the wine is rendered turbid. Soaking filter- 

 paper in the reagents above mentioned, and placing 

 a drop of the wine on the paper, is mentioned as a 

 mode of applying this test. 



New Method of preparing Vermilion. A 

 new and convenient preparation of this beauti- 

 ful compound of mercury and sulphur is pro- 

 posed by O. Hausamann, who has recently 

 been studying the subject anew. A solution 

 of corrosive sublimate is forced into an excess 

 of dilute ammonia, forming a white precipitate 

 of arnmonio-mercuric chloride. This precipi- 

 tate settles in flakes to the bottom of the ves- 

 sel, and the supernatant fluid contains chloride 

 of ammonium and the excess of ammonia. 

 The precipitate is stirred up with this fluid, 

 and a little more than enough of a concen- 

 trated solution of hyposulphite of soda is added 

 to dissolve the precipitate. On warming the 

 solution in a capsule, vermilion at once begins 

 to separate ; the heating is continued until a 

 thin pasty mass is obtained. Vermilion pro- 

 duced at a temperature of 120 to 140 Fahr. 

 is of a lighter color. 



Improvements in Chemical Apparatus. 

 Having experienced considerable difficulty 

 from the tendency of the flame in the ordi- 

 nary Bunsen burner to retreat within the tube, 

 under a low pressure of gas, President Henry 

 Morton has devised a modification of the old 

 burner which entirely removes this drawback. 

 In an article on the subject published in the 

 American Chemist, he says: 



It is well known that to secure a jet of water or 

 of any other fluid whose particles shall move with 

 equal velocities in all parts, and thus avoid currents 

 and eddies, it is only necessary to make the orifice 

 of efflux an aperture in a thin wall. 



Following out the idea above indicated, I made a 

 burner of a bore rather large compared with its 

 height, and then drew in its upper edge into the 

 form of an open-ended thimble, so contracting the 

 orifice of escape to about two-thirds the area of the 

 tube, and rendering this orifice practically an open- 

 ing in a thin horizontal wall or plate. 



The results of this modification far surpassed my 

 anticipations. A burner thus constructed gives a 

 perfectly non-luminous flame with gas pressures va- 

 rying between 1.5 and 0.1 inch of water, and with 

 the lowest of these pressures cannot be made to re- 

 treat by the most violent handling in the way of 

 sudden movement or waving about in the air, even 

 when this violence is carried to the extent of ex- 

 tinguishing the flame altogether. 



Under like conditions of pressure, a burner of the 

 ordinary construction is made to retreat by a slight 

 draught of air, or a very moderate amount of motion. 



An important apparatus for the determina- 

 tion of the melting-point has been invented by 



