XO'I'E
ON LII'SEGAX'G RINGS I N STRAIXEL) GEL BY 13. F. BURTON AND G. C . BELL
The article on the Liescgang Phenomenon by Hatschek in the Second Report on Colloid Chemistry issued by the British Association Committee, closes with these words: "The experimental reproduction and elucidation of natural periodic structures should for a long time to come be one of the most fruitful fields for applied colloid chemistry. It seems probable that investigation will have to he extended to gels made anisotropic by stress, since it is cvidcnt that most of the gel-like constituents of organisms are in such a condition, a t least during long periods." Ahoiit the time that this was writtcn experiments were being carried 011 here 011 various phases of this phenomenon, and in particular the formation of the Liescgang rings in stretched gelatinc was tricd. The gelatine filrn, impregnated with potassium chromate in the iisual way, was formed on a shcct of thin rubber instead of 011 a glass ?lide. 'I'hc ruther wts held hct clamps so that it could l i e stretched parallcl to a giveit direction. After the filni had ljecn stretched thus and while still stretched, tlic drol) of silver nitrate solution was allowed t o dro pan the central portion. 7'he aceonipanying photogrnpli gives the appcarance of the resulting rings. 'I'he longer dimension of the cllipse is in the direction of the stretching force. 'I'his arrangernent is prolxhly just what onc might expect but it v x m s to be one experiment along the line siiggrsted hv Hatschek.
