546 S. Taker — Growth of Crystals. 



A porous battery cell was placed bottom up in a glass jar, 

 about three-fourths full of a saturated solution of copper 

 sulphate, and a piece of paraffine-coated cardboard was cut to 

 fit snugly around the cell and rest on top of the jar, as shown 

 in figure o. The purpose of the cardboard was merely to 

 prevent evaporation from the surface of the solution in the jar. 

 The battery cell was 18 centimeters high and 8 centimeters in 

 diameter while its walls averaged 6 millimeters in thickness. 

 The stem of a glass funnel was inserted through a small hole 

 drilled in the bottom of the cell so that the solution could be 

 replenished and kept at the same elevation. The solution was 

 slowly drawn up through the capillary pores of the cell allow- 

 ing evaporation to take place from the exposed surface. 

 After a couple of days a coating of copper sulphate began 

 to form here and there in irregular spots. These spots grad- 

 ually increased in size and thickness to form thin crusts, and, 

 later, groups of short needle-like columns of copper sulphate 

 normal to the surface of the cell, could be observed gradually 

 pushing the crusts outward. The columnar crystals also 

 appeared in large and small groups elsewhere on the surface 

 of the cell, and on the outer ends of some of these, small 

 fragments of the cell could be distinguished. After about ten 

 days narrow cracks were seen forming in the walls of the cell. 

 At first they seemed, for the most part at least, to be open 

 fissures, but the openings were gradually filled with copper 

 sulphate so as to form veinlets, and, as the veinlets became 

 larger, it could be seen that the copper sulphate crystals were in 

 the form of needle-like columns or fibers with their axes normal 

 to the walls of the fracture. The veins were usually enlarged 

 by growth from both sides, as was shown by the presence of an 

 irregular parting near the center marked by a line of small cell 

 fragments. Occasionally where one side was cut off from 

 additional supplies of solution the crystals would grow without 

 break across the entire vein. In structure and appearance 

 these veins closely resemble the asbestos veins in serpentine, and 

 this suggests that the latter have possibly grown out from the 

 walls in a somewhat similar manner. In places the veins give 

 way to a brecciated zone in which the individual fragments 

 are separated from one another and held in place by the copper 

 sulphate. When the experiment was discontinued some of the 

 veins had a width of over 3 millimeters, and the columnar 

 crystals growing normal to the surface of the cell had a length 

 of about 1 centimeter. 



After several attempts to break glass receptacles with grow- 

 ing crystals a method was devised that proved successful. In 

 this experiment crystals of copper sulphate were grown in a 

 bulb-shaped chamber 4 - 5 centimeters in diameter, blown in a 



