CHEMISTRY — JONES. 215 



posed that when a salt, say a sulphate, is treated with an acid, say nitric acid, 

 that a part of the sulphate is transformed into nitrate, the amount depending 

 on the amount of nitric acid present relative to the amount of salt. As the 

 amount of nitric acid is increased the amount of the sulphate would gradu- 

 ally decrease until, when a large excess of nitric acid is present, practically 

 all of the sulphate would be transformed into nitrate. The results obtained 

 in this part of the spectrum work would indicate that the above conclusions 

 are not correct. The nitrates of certain metals, notably of uranium, have a 

 different spectrum from the sulphates, acetates, etc. If when uranyl nitrate 

 was treated with sulphuric acid a part of the nitrate was transformed directly 

 into sulphate, both the nitrate and the sulphate bands would be found upon 

 the spectrogram. If only a small amount of sulphuric acid were added to 

 the nitrate there would be only a small amount of the nitrate transformed 

 into sulphate. Consequently, the nitrate bands would come out relatively 

 strong and the sulphate bands relatively weak. As the amount of sulphuric 

 acid present was increased, more and more of the nitrate would be trans- 

 formed. The nitrate bands would, consequently, become weaker and weaker 

 and the sulphate bands stronger and stronger, until finally practically only 

 the sulphate bands would be present. The facts are directly at variance with 

 these predictions. 



When uranyl nitrate is treated with a relatively small amount of sulphuric 

 acid, there is in the resulting spectrogram neither nitrate-bands nor sulphate- 

 bands, but bands intermediate in position between the tzvo. By the addition 

 of more or less sulphuric acid these bands can be made to occupy any posi- 

 tion between those of the nitrate and those of the sulphate. 



Work on the absorption spectra of solutions, which has now been extended 

 to about 5,000 solutions, shows that any given absorption bands are charac- 

 teristic of a given chemical condition. Indeed, this seems to hold about as 

 well for the absorption spectra of solutions as for the emission spectra of 

 the elements. This being the case, the conclusion is forced upon us that 

 between the nitrate and the sulphate there is a whole series of systems or 

 compounds, for the most part too unstable to isolate, yet existing in solution, 

 as is shown by their action on light. These may be sulphonitrates or nitro- 

 sulphates; this question can not be answered at present, because these sys- 

 tems or compounds are too unstable to isolate chemically. The chemical 

 equations used to express chemical reactions do not take into account these 

 intermediate systems. As is well known, these equations express only the 

 beginning and the end of chemical reactions and do not take into account the 

 intermediate stages. 



A sufficiently large number of examples illustrating the above point have 

 been brought to light to justify drawing some conclusion with reference to 

 chemical reactions in general. This gradual change in the position of the 

 bands has been noted when uranyl nitrate is treated with sulphuric acid, with 

 hydrochloric acid, or with acetic acid. It has also been found when uranyl 

 and uranous acetates are treated with various acids, and when uranous and 



