NATURAL SCIENCE NEWS. 



Producing Pearls. 



Peeling pearls is a little trick 

 which Parisian jewellers have re- 

 duced to a science. They will take 

 a pearl which is apparently so im- 

 perfect that it is scarcely market- 

 able, and with a skill bordering on 

 the marvelous, will peel off the 

 outer layer and develop a lovely 

 gem. 



A pearl is made up of layers of 

 "nacre" and animal tissue. The 

 nacre is that beautiful iridescent 

 substance which gives to mother 

 of pearl and the lining of sea shells 

 their chief beauty, and it is especi- 

 ally attractive in the pearl oyster. 

 The layers of nacre and animal 

 tissue alternate, so that the skilled 

 jeweller can peel an ugly, discol- 

 ored pearl and make of it quite 

 another jewel. The tools employ- 

 ed are a sharp knife, extremely 

 delicate files, soft leather and 

 pearl powder. The layer of nacre 

 is hard and difficult to cut, but the 

 pearl renovator chips it off bit by 

 bit, feeling his way with the edge 

 of his knife, for the layer is too 

 thin to be seen by the unaided eye. 



In one of the workshops of Chi- 

 cago is a man who is specially de- 

 voted to pearls. He claims that a 

 perfect pearl is the most beautiful 

 of gems and says that the time is 

 coming when pearls will be fash- 

 ionable again. He exhibits with 

 some pride a large pink pearl and 

 said that it had been artificially 

 started. This brought out the 

 fact that in China and Japan pearl 

 oysters are not only cultivated, but 

 are forced to produce pearls. 



A pearl is the result of an oyster's 

 efforts to remove a source of irri- 

 tation. If a grain of sand or some 

 other hard substance finds its way 

 into the shell the oyster begins 

 coating it with nacre, which gives 

 the irritating intruder a smooth 

 exterior. The oyster deposits 

 nacre over the offending object as 

 long as it remains a source of irri- 

 tation, and the Chinese have taken 

 advantage of this peculiarity of 

 the solitary mollusk. They make 

 little pellets of earth which have 

 been dried and powered with the 

 juice of camphor seeds, and dur- 

 ing May and June plant these in 

 the oyster. The shell is opened 

 with a mother-of-pearl knife, care 

 being taken not to injure the oys- 

 ter, and the earth pills are laid un- 

 der the oyster's beard. The treat- 

 ed mollusks are then placed in 

 canals and pools and left undis- 

 turbed until November, when they 

 are dredged up, opened, and the 



nacre-covered pellets removed with 

 sharp knives. The pellets are us- 

 ually found fastened tightly to the 

 inner surface of the shells. 



The Chinese pearl farmer then 

 turns jeweler. He drills a little 

 hole into the pearl at the place 

 where it was fastened to the shell 

 and removes the dirt. The cavity 

 is filled with yellow rosin, and the 

 opening sealed neatly with a tiny 

 bit of mother of pearl. 



But a Frenchman has improved 

 on this method. He found that 

 the Chinese killed many oysters by 

 forcing the shell open to deposit 

 the earth pellets. The ingenious 

 Frenchman bored holes in the 

 shells of pearl oysters with a small 

 drill and then introduced through 

 the opening little globules of 

 glass. He plugged the holes with 

 corks and left the oysters alone to 

 manufacture pearls. In six months 

 the glass nuclus was covered with 

 a pearly deposit, and the French- 

 man reaped a beautiful harvest of 

 pearls. He did not have to bore 

 holes in the pearls to remove the 

 centre, and his product brought 

 higher prices than the pearls made 

 by the Chinese. 



These artifical pearls have much 

 of the lustre and beauty of the real 

 gems, but are sold at a much lower 

 rate by honest jewellers. Experts 

 can color pearls black, pink, gray, 

 and other colors by the use of 

 chemicals. For instance, a pearl 

 put in nitrate of silver turns black. 

 But pearl raisers know a trick 

 worth two of that. Certain kinds 

 of fresh water mussels bear pink 

 pearls, and pearl oysters produce 

 different colored pearls, according 

 to the part of the oyster which is 

 irritated by the foreign substance. 

 The artifical pearl producer knows 

 this and plants his seed according- 

 ly. In Washington is an artificial 

 pink pearl as large as a pigeon's 

 egg, and its heart is a bit of bees- 

 wax. 



Perfectly round pearls which 

 weigh over twenty-five grains each 

 are scarce and command large 

 prices, but such pearls are natural. 

 Artifical pearls are usually flat on 

 one side. — The Mineral Collector. 



Field Columbian Museum. 



Yesterday was the first anniver- 

 sary of the opening of the Field 

 Columbian Museum. The day was 

 marked by an attendance of 4,500 

 visitors. The attendance during 

 the year was 451,088 and the ex- 

 pectation of the trustees and Di- 

 rector Skiff that it would reach 



nearly half a million was realized. 

 The number of paid admissions, 

 was 34,840. 



The average daily attendance, 

 counting free and pay days, was 

 1,243 and the average daily attend- 

 ance on pay days was 134. The 

 largest number of visitors on any 

 one day was 15,835, on June 3, 

 1894, the day after the opening. 

 The smallest attendance was on 

 Feb. 7, 1895, the day of the sever- 

 est blizzard of the winter. Into 

 the big building only six persons 

 came that day and all were women. 



Since the opening, of the Mus- 

 eum many accessions have been 

 made to it. The most important 

 in the anthropological line was the 

 contents of the Hopewell mound 

 in Ohio. The Allison V. Armour 

 expedition to Yucatan brought to 

 the Museum material from the 

 ruins in Yucatan. About two 

 weeks ago the government of Ni- 

 caragua presented a collection of 

 material from that country. De- 

 partments of microscopy, photo- 

 graphy and printing have recently 

 been opened. An Egyptological 

 division, occupying one hall and 

 two alcoves, has been made in the 

 anthropological department. 



The Museum has started the 

 publication of scientific works, and 

 there are four now in press. The 

 first one out will probably be -'The 

 Authentic Letters of Columbus," 

 by William E. Curtis, an honorary 

 curator. 



The landscape on the north and 

 south sides of the Museum has as- 

 sumed a new appearance. All the 

 trees have been removed and the 

 avenues leading to the entrances 

 are entirely devoid of shade. 

 When the sun was hottest yester- 

 day afternoon visitors walked along 

 the side of the building to be in 

 shade and a park policeman stood 

 in the shadow of the Caesar mon- 

 ument. — Chicago Record, June jd. 



Cleaning Shells: — A corres- 

 pondent in an old copy of Random 

 Notes writes: "I have lately tried 

 an experiment in cleaning shells. 

 I boiled some cones and a few oth- 

 ers for three or four minutes in a 

 strong solution of potash, and the 

 epidermis came to pieces and fell off, 

 leaving the shell clean and smooth, 

 with no evil effect at all. Three or 

 four ounces of Babbitt's potash to 

 a pint of water is about the proper 

 strength. (The mixture may be 

 saved and used many times.) 

 Scrub the shell with a stiff brush, 

 and when it is dry rub with a cloth 

 very slightly oiled, to obtain a fine 

 gloss. " 



