On certain proteid and albuminoid reactions and their significance / by J.W. Pickering.

  • Pickering, John William.
Date:
1893
Catalogue details

Licence: Public Domain Mark

Credit: On certain proteid and albuminoid reactions and their significance / by J.W. Pickering. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    17/38 (page 361)
    actions with cobalt salts are displaced by nickel salts, and these again by copper salts yielding in turn their respective colour reactions. III. The Reactions of the Salts of Cobalt, Nickel and Copper with Certain Proteid Decomposition Products and Allied Bodies. Biuret which has the known chemical formula of acts with salts of cobalts as stated below. re- Cobalt sulphate + Ammonia Cobalt sulj)hate + Ammonia + Potash Cobalt sulphate + Potash Biuret Play of colours commencing at the violet, rapidly changing to blue then a pale claret-red solution and a green precipitate; excess of ammonia gives a yellow and a red-brown solution with a green precipitate Transient violet changing to blue with a blue precipi- tate, and a purplish solution. The pre- cipitate changes to green on standing Transient violet changing to blue solu- tion, then a fine blue precipitate and a purplish solution. The ppt. changes to green on standing The copper sulphate reaction of biuret is well known as the “ Biuret Reaction,” while Gnezda has shewn that nickel .sulphate with ammonia and biuret gives a blue solution which changes to orange on the addition of potash, in this respect giving the same colour reactions as proteids- Biuret yields negative results with nickel sulphate and tetraethyl- ammonium hydroxide, similar negative results are given with cobalt sulphate and this reagent, it gives however with copper sulphate and the same reagent a pink solution. Alloxan yields negative results with the sulphates of copper and nickel and the hydroxides of ammonium and potassium. With cobalt salts it reacts as understated. Cobalt sulphate -f Ammonia Cobalt sulphate -1- Ammonia + Potash Cobalt sulphate -f Potash Alloxan With traces of ammonia a violet precipitate and a rose-red solu- tion. The precipitate is soluble in ammonia giving a pink solu- tion, which changes redder till it becomes a brilliant orange-red. The violet precipitate when ex- posed to the atmosphere for 24 hours retains its colour, after 48 hours it becomes a leaden grey The rose-red solu- tion becomes on addition of potash aheliotrope-purple, excess of potash gives a violet solu- tion Rose-red solution. If the KOH is added as a few drops, a violet ppt. soluble in potash to a rose-red solution, more potash gives a heliotrope pui-jile, and still more a violet solution