76 Intelligence and Miscellaneous Articles. 



casioned by disengagement of gas, and the mass , becomes black, 

 because the chrome red, as it may be technically called, appears 

 black when it is hot. The yellow chromate is to be added until 

 all the nitre is decomposed. Care must be taken not to heat the 

 crucible too strongl)', because at too high a temperature the colour 

 loses its beauty and becomes brown. The crucible is then to re- 

 main for some time, in order that the chrome red, which is heavy, 

 may deposit, and the saline mass, which is composed of chromate 

 of potash and nitre, is to be poured off while fluid. This mass may 

 be used again for the preparation of fresh chromate of lead. The 

 chrome red remaining in the crucible is to be well washed with 

 water, and dried. It is essential not to leave the saline solution long 

 in contact with the red powder ; because by this it loses its splen- 

 dour, and acquires an orange tint. The powder, however, subsides 

 so fast on account of its density and crystalline state, that this in- 

 convenience is easily remedied by increasing the number of wash- 

 ings. The chrome red thus obtained is a powder of a superb cin- 

 nabar red colour ; when it is examined by the light of the sun, it 

 appears to be composed of small crystalline scales. There is no 

 doubt that it will entirely supersede the use of cinnabar as soon as 

 it can be obtained at a lower price. Yellow chromate of lead dis- 

 solves plentifully in a strong boiling solution of potash. After some 

 days this solution deposits groups of red crystals composed of small 

 plates, which consist of subchromate of lead, and of neutral chro- 

 mate, as has been stated. 



PROTOXIDE OF COPPER. 



The simplest and easiest method of obtaining protoxide of copper 

 is the following : — Dissolve the copper in muriatic acid, to which 

 small portions of nitric acid are to be added; afterwards evaporate 

 to dryness, and heat the chloride obtained to its fusing point. It 

 is thus converted into brown crystallized chloride. It is afterwards 

 to be fused, ten parts with six of dry carbonate of soda, in a covered 

 crucible at a low red heat. The mass is to be treated with water 

 to dissolve the common salt formed ; the protoxide of copper sepa- 

 rates in the state of an uncrystalline powder of a fine red colour, 

 which is to be washed and dried. 



If muriate of ammonia be added to the above mixture, all the 

 chloride is reduced, as will readily be foreseen, to metallic copper, 

 which separates in a very divided and spongy state, when the mass 

 is dissolved in water. 



TITANATE OF IRON. 

 With the intention of discovering a more convenient method of 

 separating titanic acid from titanate of iron, the mineral well pow- 

 dered was fused with several times its weight of chloride of calcium 

 in a strong red heat. Chloride of iron constantly escaped between 

 the crucible and the cover, which rendered the weak flame of the 

 charcoal white and brilliant, and deposited upon the sides of the 

 crucible sublimed oxide of iron possessing a metallic lustre. The 



black 



