WILLIAMS ON THE PREPARATION OF UREA. VI1.-Note on the Preparation 'of Urea. By JOHN WILLIAMS. HAVINGhad occasion to prepare rather large quantities of urea I found that the result constantly fell considerably short of what I considered a satisfactory one. This led me to consider if the ordinary mode of preparation could not be improved. upon. The result of my experiments is that cyanate of lead is F2 64 GLADSTONE ON THE PYROPHOSPHORIC AMIDES. better adapted for the purpose than the mixture of salts gene- rally present in solution when the usual process is adopted. I proceed in the following manner :-I prepare the cyanate of lead by fusing cyanide of potassium of the best commercial quality (containing about 90 per cent. of real cyanide) at a very low red heat in a shallow iron vessel; red lead is added in the usual manner by small quan- tities at a time with constant stirring so as to prevent the temperature rising too much during the operation.I prefer cyanide of potassium to ferrocyanide for many reasons but mainly because the temperature can be kept down to the lowest point. The cooled and finely powdered product is exhausted with successive portions of cokd water the liquid filtered and nitrate of barium added. Carbonate of barium is thus precipitated. The mother-liquid treated with nitrate of lead yields pure cyanate of lead; this em be washed thoroughly and dried at a gentle heat and preserved for use. Unlike cyanate of potas-sium it is a peimanent salt and could be produced as a com-mercial product at a moderate price if required. To prepare urea it is simply necessary to digest with snffi-cient water at a gentle heat equivalent quantities of cyanate of lead and sulpliate of ammonium filter and evaporate. I have found the result most satisfactory. The compound ureas may in like manner be produced by substituting the sulphates of the compound ammonias for the ordinary snlpliate of ammonium ; the experiment has been tried and found successful.