T (average Rays (given out in Element Atomic time-period--half each Weight transformed) decomposition) --------------------------------------------------------------------- Thorium 232.1 2.2 × 10^{10} yrs. Alpha Mesothorium I 228 6.7 yrs. Beta, Gamma Mesothorium II 228 6.2 hrs. (?) Beta, Gamma Radio-thorium 228 1.90 yrs. (?) Alpha Thorium X 224 3.64 days Alpha Thorium (Emanation) 220 54 sec. (?) Alpha Thorium A 216 .14 sec. (?) Alpha Thorium B 216 10.6 hrs. (?) Beta, Gamma Thorium C 212 60 min. (?) Alpha Thorium D 208 3.2 min. (?) Beta, Gamma Thorium E (End-product 208 ............... ............... thorium-lead) --------------------------------------------------------------------- Transcriber’s Notes Punctuation, hyphenation, and spelling were made consistent when a predominant preference was found in the original book; otherwise they were not changed. Simple typographical errors were corrected; unbalanced quotation marks were remedied when the change was obvious, and otherwise left unbalanced. This book uses terminology that was current at the time of publication, and reflects the state of science as it was understood by the author at that time.