Arthur R. Hitch
1918 Journal of the American Chemical Society  
I 195 ranged in distinct layers. Rarely were the gaps between these bands free from crystals. Liesegang' insists that silver chromate bands in gelatin only when defmite small quantities of acid are present. The great field opened by the use of basic gels leaves to this observation a rather limited application. Davis,2 in securing bands of colloidal mercury, argues that there must have been supersaturation with this same colloid. In this connection my experiments with bands of colloidal gold
more » ... colloidal gold might be studied. Throughout the red-blue-green bands of colloidal gold and the gaps as well were countless, gleaming, yellow crystals of gold. Liesegang's "dead space" experimenta confirms the theory advanced in this paper. He filled a glass tube (open a t both ends) with gelatin containing 10% o f sodium chloride. This tube was then immersed in a solution of silver nitrate which diffused into the gel from both ends of the tube precipitating silver chloride in two bands. However, these two bands of silver chloride did not meet in the middle of the tube. A clear dead space remaining in the center of the tube contained no sodium chloride at all. The salt originally there had diffused away in opposite directions. A dead space was not formed when a gel oontaining a nondiffusing substance such as albumin was immersed in metaphosphoric acid, Those who do not accept the theory I have advanced will, a t least, find in the experimental evidence new and superior methods for investigating the problem. OBZRLIN, OHIO.
doi:10.1021/ja02241a007 fatcat:75cobgswezhkhooguemverj7xu