From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Comparison table of motor spirits from Summer 1933, detailing their properties and octane numbers.
| Identifier | ExFiles\Box 27a\4\ Scan265 | |
| Date | 1st January 1933 | |
| MOTOR SPIRITS SUMMER 1933 Brand S.G @ 60°F 10% @ 35% @ 65% @ 90% @ Octane No Shell No.1 .7382 62°C 91°C 125°C 162° 67 Shell Mex. .7401 68 101 136 170 65 B.P.Plus .7364 63 95 133 173 73 B.P.Com .7418 63 100 144 179 67 Pratts H.T .7345 61 95 130 168 68 Pratts Com. .7425 64 104 141 176 67 Pratts Ethyl .7358 63 92 124 161 77 Pratts B.M .7581 67 91 127 170 73 Clev. No.1 .7383 58 99 144 183 68 Regent .7574 66 107 148 185 73 Regent Super .7400 56 90 128 172 76 Regent B.M. .7496 61 91 125 171 77 Glico-Ethyl .7351 62 93 123 157 77 Glico Com. .7435 63 102 141 178 67 Nat. Ben. .7809 74 93 116 161 75 Citex Loolmotor .7539 59 70 121 164 80 Citex Com. .7354 66 100 131 167 63 Citex B.M. .7597 69 98 137 196 64 Power Premier .7348 58 96 133 171 75 Power Com. .7434 66 106 142 173 68 R.O.P. Zip .7426 75 101 128 160 67 R.O.P. Com .7407 65 104 136 164 69 (Continued) ENCLOSURE N°210 | ||