464 



The Chemical Composition of Pearls. [Mar. 22, 



effervesce like a seidlitz. powder — though much less strongly — when 

 brought into contact with strong vinegar, and thus on their being 

 diluted with water may be transformed into what might be called a 

 cooling lover's potion, while from the organic matter having at the 

 same time as the mineral constituents been minutely subdivided, its 

 presence would scarcely be recognisable in the solution.]* 

 2nd. Composition of cocoa-nut pearls. 



Qualitative analyses of pearls found in cocoa-nuts have been 

 published by both Dr. J. Bacon and Dr. Kimminis.f But their 

 analyses differ somewhat, for while Bacon found carbonate of lime and 

 an organic substance akin to albumen, Kimminis met with nothing 

 whatever in them except pure carbonate of lime. We subjected a 

 portion of a garden pea sized cocoa-nut pearl, weighing 14 grains 

 (kindly given to us by Messrs. Streeter) to analysis, and found that, 

 like shell-fish pearls it consisted of carbonate of lime, organic matter 

 (animal), and water. 



The pearl which we examined was sent to Messrs. Streeter by their 

 agent at Singapore (the same place from whence Bacon obtained his 

 specimen), and as we stated last year (on June the 8th), when we 

 exhibited at the soiree of the B-oyal Society both drawings and micro- 

 scopic sections of it, we are exceedingly sceptical of the pearl we 

 examined being in reality the product of a cocoa-nut, for the following 

 reasons. It had all the external appearances of the pearls found in 

 the large clams (Tridacua gigas) of the Southern Ocean, being 

 perfectly globular, with a smooth, glistening, dull white surface, and 

 resembling them exactly in microscopic structure. Besides which in 

 chemical composition it bore no similarity to cocoa-nut milk, to 

 which it is supposed to be related. For cocoa-nut milk is said to 

 contain both the phosphate and the malate, but not the carbonate of 

 lime. That there are pearls found in cocoa-nuts we do not presume 

 to deny; all we mean to say is that we are doubtful if the specimen 

 we examined had such an origin. J 



3rd. As regards mammalian pearls. 



These so-called pearls have been met with in human beings and in 



* Added March 27th, 1883. 



f See 1 Proceedings of the Boston Society of Natural History,' vol. 7, 1861, p. 290 ; 

 vol. 8, 1862, p. 173 ; ' The Tropical Agriculturist,' April, 1887 ; and ' Nature,' 

 16th June, 1887 (Dr. Hickson and Mr. Thiselton Dyer) . 



X Since this paper was in type I have kindly had my attention drawn by Dr. 

 Hickson to a letter from J. Gr. F. Kiedel, of Utrecht, in ' Nature,' loth September, 

 1887, in which he states that in 18S6, while in North Celebes, he found a pearl " in 

 the endosperm of the seed of the cocoa-nut." And that he has in his possession 

 "twomelati pearls (Jasminium sanilac) ; one tjampaka pearl (Michelia Ion gif olid) ^ 

 found in the flowers, according to the natives. One of the cocoa-nut pearls has a 

 pear-shaped form, the length being 28 mm. The common name amongst the natives 

 for this kind of pearl is mustika." — Gr. H., 1st March, 1888. 



