( 464 ) 
2C15 NO,  S3E€1GNO,. 4 C13 NO,. 
compound compound compound 
chloro-nitro-benzoic acid 165° 138° 181°.5 
chloride solid — 51° 
methyl ester 75° 48°.5 83° 
amide 178° 154° 156° 
mono-methylamide 174° 134° 136°.5 
dimethylamide 124°.5 104°.5 113°,5 
Chemistry. — “The Enantiotropy of Tin” (IV). By Dr. Ernst 
Corner (Communicated by Prof. H. W. Bakuurs RoozeBoom). 
1. At the 65 meeting of “Deutsche Naturforscher und Aerzte” 
held at Nürnberg in 1893 1), it was stated by H. Srockmerer that 
the roof of the post-office at Rothenburg a. T., which is made of 
cast tin plates was found to be corroded (suffering from “tin-plague”’ ; 
compare proceedings 1899, p. 152). | 
After consulting the older literature on this subject, he attributed 
the phenomenon to the low temperature which had prevailed at 
Rothenburg. 
STOCKMEIER, however, also communicated, that the roof of the 
town-hall tower adjoining the post-office which is made of flattened 
tin plates had remained perfectly sound although exposed to the same 
low temperature. To explain the phenomenon, STOCKMEIER mentions 
a research by Lewatp*) who attributes the disaggregation of tin at 
a low temperature, as noticed by Frirzscue in St. Petersburg, to 
its shape (blockform) and mode of manufacturing and not, as he 
emphatically states, to the physical properties of the “matter”. 
LEWALD says: “es ist nun nicht richtig zu sagen: Zinn hat die 
Eigenschaft bei circa — 35° C. seine Struktur zu ändern und zu 
zerfallen, sondern bloss Zinn, welches in Blockformen gegossen, 
zeigt dieses Verhalten.”’ 
He believes, that the tincrystals formed on cooling the cast mass 
get into a state of tension. “Es muss daher einen Temperaturgrad 
geben, bei dem die Spannung der Kristalle einen solchen Grad 
erreicht, dass sie zum Zerfallen der Blöcke führt.” 
*) Verhandlungen der Gesellschaft deutscher Naturforscher und Aerzte. 65e Ver- 
sammlung zu Nürnberg (11—15 Sept. 1893), S. 97. 
2) Das Ausland 1879, S. 71 Dinglers polytechn. Journal 196 (1870) 369. 
