Intelligence and Miscellaneous Articles. 157 



It appears that the analyses of Varrentrapp only, give iron as pre- 

 sent in these substances, and which is essential to the production 

 of the blue colour of ultramarine : lapis lazuli is well known to con- 

 tain iron pyrites. 



M. Eisner has analysed the blue and green varieties of ultramarine 

 from Nuremberg, and he found them to be composed as follows : — 

 Blue Ultramarine. Green Ultramarine. 



Silica 40-0 39'9 



Alumina 29*5 30-0 



Soda 23-0 25-5 



Sulphuric acid .... 3*4 "4 



Sulphur 4-0 . : 4'6 



Peroxide of iron . . 1*0 '9 



100-9 101-3 



These contained traces of chlorine, potash, lime and magnesia. These 

 analyses show that there is much more sulphur present than is re- 

 quired for the production of a simple sulphuret of iron ; this excess 

 of sulphur can be combined only with the sodium ; and it results 

 also from the analysis, as is^also shown by synthetical researches, 

 that sulphuret of sodium is not less necessary than sulphuret of iron 

 to the production of ultramarine. — Journal de Pharm. et de Chim., 

 Avril 1842. 



PREPARATION OF OXICHLORIC ACID. BY M. AD.NATIVELLE. 



Oxichloric acid, which is so useful as a reagent, M. Nativelle re- 

 marks, is seldom to be found in laboratories ; and he supposes this 

 to be owing to the small quantity of it which is obtained by em- 

 ploying the proportion of sulphuric acid usually recommended in 

 chemical works : he gives the following process as separating the 

 whole of the acid from the oxichlorate of potash : — 



Put into a glass retort 500 parts of oxichlorate of potash reduced 

 to powder, deprived as much as possible of chlorate; add 1000 

 parts of sulphuric acid of specific gravity 1*845, and 100 parts of 

 distilled water ; this small quantity of water is not indispensable, for 

 it will be shown that, by omitting it, oxichloric acid is obtained in 

 the crystalline state. An adopter with a long tube is to be passed 

 into a tabulated retort, surrounded with cold water ; the apparatus 

 must not be luted with any organic substance, for the oxichloric 

 acid gas coming into contact with it while hot decomposes it and 

 produces slight detonations ; when proper vessels are employed lute 

 need not be employed, but, when required, filaments of amianthus 

 answer the purpose. The oxichlorate is to be carefully heated ; it 

 readily dissolves, and the fire must be regulated so as to prevent the 

 oxichloric acid from carrying over with it too much sulphuric acid. 

 The best method of regulating the operation is to keep below the 

 boiling point ; but little sulphuric acid goes over, for oxichloric acid 

 volatilizes at 284°, which is much lower than the temperature at 

 which sulphuric acid distils. The operation is complete when the 

 residue in the retort is transparent and colourless, or when the pro- 

 duct drops very slowly and the temperature of the retort is nearly 

 sufficient to volatilize sulphuric acid ; the weight of the product de- 



