270 ANNUAL OF SCIENTIFIC DISCOVERY. 



The action of the acid is not less constant upon the poppy oil. Ex- 

 perience proves that the development of heat with this oil is really 

 86. 4, instead of 71 to 74 indicated by direct experiment. 



This method of analysis may be applied to the olive oils of com- 

 merce ; and if these oils are falsified with poppy or other oil, the anal- 

 ysis can be made if we are assured of their qualitative composition. 

 But in this case, how shall we ascertain the mixture of the two acids ? 

 To answer this question, I have determined the elevation of tempera- 

 ture produced by most of the pure oils. 



It results from my researches that the oil of ben* and of suet give 

 almost exactly the same elevation of temperature as the olive oil. 

 The other oils differ so considerably from olive oil in this respect, we 

 may easily distinguish it in fine, the siccatives or dying oils give a 

 much greater heat than the non-siccatives. 



The oil of ben and suet oil are not mixed with olive oil, consequent- 

 ly if we find that the olive oil gives more than 42 of heat, with a 

 mixture of 10 cubic centimetres of sulphuric acid (the normal tem- 

 perature being 25) this oil cannot be pure. M. Maumene Compt. 

 Rend. xxxv. 



QUANTITATIVE DETERMINATION OF IODINE. 



Benzine possesses the property of dissolving iodine wherever it 

 meets with it in a free state. The color presented by this solution is 

 bright red, which becomes deeper in proportion to the amount of io- 

 dine contained in it. When exposed to the air, the iodine is volatil- 

 ized, and the solution becomes discolored. If a few drops of nitrous acid 

 be put into a liquid containing an alkaline iodine, and after the mixture 

 is effected 2 or 3 grms. of benzine be added to it, and the whole 

 strongly agitated, the benzine soon rises to the surface of the liquid, 

 exhibiting a magnificent color, arising from the iodine which it brings 

 with it. This reaction renders it possible to determine with the great- 

 est ease the presence of 1 milligrm. of iodine in 4 litres of water. 

 Neither ether nor the oils of lavender, citron or turpentine, furnish 

 under similar circumstances such decisive results. Chloroform em- 

 ployed either in M. llabourdin's method, or in that of M. Grange, 

 certainly in many cases readily shows the presence of iodine ; but its 

 sensibility and the color which it acquires are far from being conclusive 

 as to the characters offered by benzine. In carefully conducted experi- 

 ments, I have been able in this way to determine the presence of io- 

 dine wherever traces of it were indicated by starch paste, and the 

 employment of benzine has always appeared to me to furnish most 

 satisfactory results. 



I will add to these observations, that if by means of benzine we 



*Tlie oil of ben is largely used as a vehicle for perfumery in Paris, being entirely 

 inodorous and tasteless , it is little known in this country, and must not be con- 

 founded with the benne oil of the pharmacopeias It is obtained from the fruit of 

 the Moringa aptera (M. oieifera), principally from Arabia. 



