How to determine omitted units in a publication
These are degrees Celsius.

To prove that, you could search JACS for the publications of the same year/issue for the temperature-related physical constants such as melting point:


Douglas et al. [1] lists m.p. of $\ce{LiF}$ as $\pu{848 ± 1 ^\circ}$, whereas currently Wikipedia lists $\pu{845 °C}$.  
Yankwich et al. [2] lists m.p. of malonic acid as $\pu{140 ^\circ}$ whereas currently Wikipedia lists $\pu{135 to 137 °C}$.


You may find further examples, but even at this point it's fairly obvious what those temperature units are. 

References


Douglas, T. B.; Dever, J. L. Lithium Fluoride: Heat Content from 0 to 900°, the Melting Point and Heat of Fusion. J. Am. Chem. Soc. 1954, 76 (19), 4826–4829. https://doi.org/10.1021/ja01648a016.  
Yankwich, P. E.; Promislow, A. L. Intramolecular Carbon Isotope Effect in the Decarboxylation of Liquid Malonic Acid Near the Melting Point. J. Am. Chem. Soc. 1954, 76 (18), 4648–4651. https://doi.org/10.1021/ja01647a050.