For storinc; paper currencies rie;id controls were in- 

 troduced in the nse of \-arioiis holders conunercialh 

 available. Unfortunately, it was found that some (jf 

 the acetate and di-acetate films used for their manu- 

 facture were not sufficiently stable and were harmful 

 to paper. In\aluable help in this preservation project 

 was received from Dr. H. .A. Pace of the Research 

 Di\'ision of the Goodyear Tire and Rubber Gompany, 

 Akron, Ohio, and from the Film Department of E. I. 

 du Pont de Nemours & Go., VViliuint;ton, Delaware. 

 ThrouE;h the cooperation of Dr. Pace it was also 

 possible to conduct fadc-ometer tests of currencN' 

 samples partially covered with ciuarter-inch Plexic;las 



filters and aluminum-foil masks. An exposure of 132 

 iiOLirs was used, and dyes were considered fadeproof if 

 no perceptible change occurred after 100 hours of 

 exposure. The tests pro\-ed that, in addition to lisht 

 filters, controlled ambient conditions are necessary 

 to assure maximum protection for paper currencies 

 on display. It appears that success has been achie\-ed 

 in protecting paper documents of \alue and ribbons 

 of decorations from the harmful effects of light and 

 other ambient conditions by eliminating sulphur 

 dioxide from the atmosphere,""' and through im- 

 pregnation with phenantrenonc.'"' 



TECHNICAL EXAMINATION OF MATERIALS 

 NONDESTRUCTIVE ANALYSIS) 



The Smithsonian is frequently faced with the 

 problem of determining the specific composition (>( 

 coins and medals. One of many methods used in 

 this research is electro-spectrographic analysis, biu 

 electric sparks may damage the surface of a coin. 

 X-ray spectrography, however, is harmless to the 

 specimen. This method permits exaunnation of the 

 coin, giving the composition of a thin surface layer 

 only. It has the advantage that it can be done in 

 10 to 20 minutes with an accuracy of a few tenths of 

 a percent.'"^ 



The method is of distinct practical use. A half eagle 

 struck in 1849 at San Francisco by Ncrris, Grieg, 

 and N'orrij had been condemned by sev'cral experts as 

 a counterfeit because of its unusual ""rippled" surface. 

 \Vhen submitted to the Di\'ision for examination, 

 certain details were noticed whicli indicated that the 

 coin was authentic and that a more thorough inves- 

 tigation was warranted. Througli the cooperation of 

 the PvCA laboratories the composition of this piece 

 was tested and compared with that of other similar 

 coins preserved in the L'nited States Mint collection 

 since 1850. The results obtained with lluorescent 



analysis ecpiipment showed that in addition to gold- 

 both silver and tin were present in considerable 

 cpiantities in all specimens tested, and there were 

 traces uf iron as well. The presence of tin in all 

 specimens tested was, of course, diagnostic and 

 [proved that all pieces examined were minted from an 

 allo\' of identical origin. 



'>.^:^ (:r ~ 





^"^!t-l 



Fig. 53. — Five-Dollar Gold Piece issued by the 

 Massachusetts and California Co.. 1849. 



Once the special composition of the allo\' becomes 

 widely known, counterfeiters may, of course, take 

 ad\'antage of this knowledge, and other non-destructive 

 tests may have to be devised from time to time. 

 .\rrangements are being made, for example, for 



""' I l.-\Ns KoTiE, "The Dur.Tbility of Papr-r." Allirmnur Papir]- 

 Rimthchau (1056), no. IL', pp. .'}77-37'). 



""John O. Hawthorne aiicl Mvron II. Wilt. .Metli.id of 

 protecting material against the cllrc ts of lii^ht. I'.S. Patent 

 L'.90r),.'-)70, Sept. 22, 195'!. 



""Dr. Bernard DeVVitt of C^oknnbia-.Soullii'rn ( iurporation. 

 Barbcrton, Ohio, analyzed on September \:\ I'l.'ili, a British 

 sovereign dated 19.57 and a Newfoundland 2-dollar gold pieee 



dateci IHJil by using the smooth surface of a United States 

 eagle of 1897 as a presumed standard of 90' , .gold and Id' ,' 

 copper. The X-ray analysis was made with a Phillips electronics 

 X-ray spectrograph. The sovereign was shown to contain 'tl .'i' , 

 i;old and K.7' ;, copper, while the 2-dollar piece was shown to 

 cont.iiii 91.7',, gold and !!.'.', copper. .\ll .specimens were 

 made a\ailable for testing Ijv Dr. Kenneth ( :. Kberly, of .\kron. 

 Ohio, 



PAPER 31 : HISTORY (JF THE N.VTIONAT, NUMISMATIC COLLECTIONS 



31 



