218 C. E. Linebarger — Nature of Colloid Solutions. 



country where the lines could easily be followed farther if they 

 existed. No snch end has ever been found for the Algonquin 

 or Iroquois beaches. They have merely been lost in the bush, 

 or rocky, scantily drifted regions, and await more careful and 

 energetic exploration. 



If shore lines are found in the highlands 50 to 70 miles 

 south of Mackinac Island, as has been reported, they must 

 have been formed by ice-dammed lakes which were drained 

 off and had disappeared before the summit of the island itself 

 emerged from the ice. The higher beaches of the Ontario 

 basin and all those of the Erie basin were probably made by 

 ice-dammed lakes. But the heavily developed and apparently 

 continuous Algonquin and Iroquois beaches, including the 

 170-205 foot beaches of Mackinac Island, — probably all one 

 line, — were made by waters which had open connection through 

 a broad strait at Nipissing with the Gulf of St. Lawrence, 

 and the Atlantic Ocean. The facts suggest a provisional 

 classification of the deserted beaches of the Great Lakes into 

 two divisions, produced by entirely different causes, and prob- 

 ably at widely separated times, namely : the higher level, 

 fragmentary and comparatively weak beaches, probably pro- 

 duced by ice-dammed lakes, and the lower, strongly developed, 

 continuous beaches of marine origin, formed, probably, long 

 after the ice sheet had disappeared from eastern North 

 America. 



Fort Wayne, Ind., Xov. 18, 1891. 



Akt. XX YI. — On the Nature of Colloid Solutions ; by 



C. E. LnSTEBARGEB. 



It seems to be the general opinion among scientists that the 

 solutions of colloid substances, such as albumen, silicic acid, 

 tungstic acid, etc., differ in their nature from solutions of 

 crystalloid substances. The great difference in the velocity of 

 diffusion of solutions of crystalloids on the one hand and of 

 colloids on the other, together with the fact that certain animal 

 membranes and parchment paper are impermeable for colloids, 

 but allow crystalloids to pass freely through their pores, led 

 Graham* to invent the names crystalloid and colloid, thus 

 dividing substances into two great classes. Graham in his 

 paper states distinctly the differences existing between crys- 

 talloids and colloids and ventures the question whether 

 the basis of the colloid state may not be in the complex 



* Liebig's Ann., cxxi, 1, 1862. 



