Publisher's Synopsis
Excerpt from Transactions of the Clinical Society of the University of Michigan, Vol. 7
To 500 cubic centimeters of freshly distilled water are added 60 degrees C 5 cubic centi meters of a 1 per cent. Solution of gold chloride and 5 cubic centimeters of a 2 per cent. Solution of potassium carbonate. As in the original method. This gold-carbonate solution is then heated almost to boiling and is kept over a ?ame because the air bubbling through it tends to cool it. The formaldehyde gas in air is then passed through it and is controlled by the action of the bellows. The solution gradually turns from water-white to a pale blush, then to apink, then to a darker red with a bluish tinge. The bubbling causes sufficient agitation in the solution to keep it well mixed all the time. If the reaction is continued too long, the color turns to a dark purple or to a muddy blue. In this modification of the method of preparing colloidal gold no attempt is made to measure the amount of formaldehyde, but the reaction is guided by the color of the solution. Such solutions of colloidal gold are uniformly clear.
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