Hydrometer tests of triton & sludge from other oils, Southern California, 1935

7 photographs of hydrometer tests of triton & sludge from other oils, Southern California, 1935. "Subject: Hydrometer tests of triton & sludge from other oils; Client: Union Oil Co.; Original Print Order: 1 ea[ch], 2 ea[ch], 1 #1, 1 #5; Size: 5x7, 8x10, 11x14; Finish: gl[ossy]; Mount: For files, no circle, enlarge tube on left to 5 3/8" [ilg], as before; #1, 2, 3, 4, are to be printed then circle as mask; Year: 1935; Job: 1-18-97" -- on envelope front. "Operator's Report Name: Dick; 7 Original Photographs - Size: 8x10; Amount: 21.00, 2x80; Extra Charges: Stromheyer" -- on envelope back.