OF ARTS AND SCIENCES. 



boiling water the salt is but slightly soluble ; but dilute sulphuric acid 

 dissolves it more readily and without decomposition, if the boiling be 

 not continued too long. Stronger acid readily decomposes the sulphate 

 by boiling. When boiled for some time with dilute chlorhydric acid, 

 the solution gradually becomes violet-red, and oh cooling deposits crys- 

 tals of chloride of purpureocobalt. Of these crystals, 



0-2825 gr. gave 0-1749 gr. CoSO, = 23-56 per cent cobalt. 



The formula Co2(NH3),„Clg requires 23-55 per cent. 



The decomposition is accompanied by effervescence from the escape 

 of gas, apparently nitrogen mixed with a smaller quantity of nitrous acid 

 vapors, and may perhaps be expressed by the equation : — 



2Co,(NH3)8(NO,),SO, + 6HC1 = Co,(NH3),,Cl, + 2CoSO, -{- 

 12OH2 + 2NO2 + 12N. 

 In this reaction we pass from a lower to a higher ammonia-base, and 

 Geuth and I have shown that we may also pass from purpureocobalt 

 to luteocobalt, or from the decamin to the dodecamin series, the higher 

 term being in each case the product of the decomposition of the lower 

 The formula of the sulphate in the new series is, as stated, Co^(NHo)8 

 (^0^)480,. The following ai'e the direct results of analysis : — 



0-6142 gr. gave 0-3596 gr. CoSO^^r 22-28 per cent cobalt. 

 0-4207 gr. gave 0-2454 gr. „ r= 22-21 „ „ 



1-5547 gr. gave 0-6785 gr. BaSo4 = 17-98 „ SO, 

 0-6960 gr. gave 0*2903 gr. water = 4-63 „ hydrogen. 

 0-4693 gr. gave 123*5 c.c. nitrogen at 9-5° C. and 754-5'"™ = 31-33 

 per cent. 



534 100-00 



On Blomstrand's view of the constitution of the ammonia-metallic 

 bases, the formula of the sulphate may be written : — 



Co, 



NH3-NO2 

 NH,-NO., 

 NH,-NH; gQ 



NH.-NO^ 

 NIL -NO., 



I shall discuss this view more fully at the close of this paper. 



