THE REJUVENESCENCE OF CRYSTALS. 285 



III 1S42, Hennaiiii Jordan sliowed that crystals taken from a sohitiou 

 and nintilatctl uradually IxH-anie repaired or healed when rei»laee(l in 

 the solution (MiiUrr Arrhir. fiir 1842, pp. 40-.j(!). rFordan's observa- 

 tions, which were published in a medical journal, do not however seem 

 to have attracted much attention from the ]>hysicists and ciieinists of 

 the day. 



Lavalle, between the years l.S.K) und IS.jS,* and Kop]), in the year 

 185.^, made a number of valuable observations bearing' on tliis interest- 

 iuii' pr()i)erty of crystals ( Liebig Ann., 1855, XCIV., pp. 118-25). In ^S'^i} 

 the subject was more thoroug-hly studied by three investigators who 

 ])nblished their results almost simnltaneously; these were ^rarbach 

 {('oinpt. rcnd.^ 185G, XLiir, pp. 7(»5-7(>(;, 8(H)-8()2), Pasteur {ib'uL, pp. 795- 

 800), and Senarmont (/7>/^/., p. 7!)!)). They showed that crystals, taken 

 from a solution and mutilated in various ways, upon being- restored to 

 the liquid became comi)letely repaired during subsequent growth. 



As long ago as 1851, Lavalle had asserted that, when one solid angle 

 of au octaliedrou of alum is removed, the crystal tends to reproduce 

 the same mutilation on the oi)posite angle when its growth is resumed! 

 This remarkable and anomalous result has however by some subse- 

 quent writers been exi)lained in another way to that suggested by the 

 author of the experiment. 



In the same way the curious experiments performed at a subsequent 

 date by Karl von Ilauer, ex])eriments which led him to conclude that 

 hemihedrism and other peculiarities in crystal growth might be induced 

 by mutilation,! have been asserted by other physicists and chemists 

 not to Justify the startling conclusions drawn from them at the time. 

 It must be admitted that new experiments bearing on this interesting 

 (pu'stion are at the present time greatly needed. 



In 1881, Loir demonstrated two very important facts with reg'ard to 

 growing crystals of alum {(Jonipf. rend., lid. xcii, p. ll()(>). First, that 

 if the iujuries in such a crystal be not too deep, it does not resume 

 growth over its general surface until those injuries hav'ebeen repaired. 

 Secondly, that the injured surfaces of crystals groAV more rapidly than 

 natural faces. This was proved by placing artificially cut octahedra 

 and natural crystals of the same size in a solution and comparing their 

 weight after a certain time had elapsed. 



The important results of this capacity of crystals for undergoing- 

 healing and enlargement and their ap})lication to the explanation of 

 interesting geological phcnoincna have been pointcMl out by many au- 



*BnU. (iM. Soc. Parin, 2^i'' sor., vol. \iii, pp. (510-18. IH")! ; Moii^iio, Cosmos, ii, 1K5;^, 

 pp. 451-56 ; CoDipl. retid., xxxvi., 1853, pp. ■19.3-i)5. 



\Wien, Sifz. Her., xxxix., 1860, ]ip. 611-22; Erdiiiaiin, Joiini. prakl. Clicm., i.xxxi. 

 pp. 356-62; jrieii, (!col. VcrhnndL, xii. pp. 212-13, etc. ; Fraukenhciin, /'o////. Ann., cxiii, 

 1861. Compare Fr. Scbarff, Poem. Ann., cix, 1860, pp. .529-38; Nvnvs Jahrb. fiir Min., 

 etc., 1876, p. 24; and W. Sanber, Licbi;/ Ann., cxxiv., 1862, pp. 78-82; also W. Ostwald. 

 "Eelubnch d. Alli;. Chem.," 1885, Bd. I, p. 738, and O. Lebmaun, "Molckiilar I'hy- 

 sik," 1888, I'.(l.i.p.312. 



