1900 G. T. Teasdale-Buckell Experts on Guns & Shooting xxxvi. 536 By Rule 46 of the proof regulations when a gun has been proved in this way it is to be marked as follows, ‘nitro proof oz. maximum’, indicating the service weight of shot to be used.

1903 Blackwood's Edinb. Mag. Oct. 512/1 In most of the better brands of nitros, what used to be a positive danger has been reduced to a very occasional discomfort.

1975 Amer. Hist. Rev. 80 1327/1 In the last eighteen months of the war [of 1914–18] Danish importation of fertilizer, readily remade into ‘nitros’ for explosives, was cut drastically.

1991 Pop. Sci. Mar. 6/1 If the Iowa's nitro was not in good, fresh condition, it could have self-ignited from mild ramming.

1916 Star of Hope xvii. 214/1 Soup, dinny and nitro.

1935 N. Ersine Underworld & Prison Slang 54 Nitro, nitroglycerine.

1950 R. Chandler Let. 18 May in R. Chandler Speaking (1966) 80 Opening a good safe (without a time lock) requires expensive and heavy tools, the finest drills either to drill out the lock or to get in the nitro if he is a peterman.

1972 J. Godey Three Worlds (1973) iii. 30 They had an old-time safe... I hit it with a fat charge of nitro.

1990 Reader's Digest June 159/1 The boom was swinging to and fro with enough nitro dangling off its end to reduce a 25-storey block of flats to rubble.

1948 Philos. Trans. (Royal Soc.) A. 241 191 The 4-amino compound was again obtained from the nitro by reduction with Raney nickel and hydrogen.]

1985 Planta Medica 4 349 It is not necessary to transform the second nitro to a ketone group to give 2,5-undecadione. A direct transformation procedure is given.

1992 Jrnl. Org. Chem. 57 272/1 The reaction..having electron-withdrawing groups such as bromo, cyano and nitro at the 13 position did not afford any reaction product.

1932 G. Burrard Mod. Shotgun III. xv. 312 Previous to 1925 all ordinary sporting guns of British manufacture were submitted to three different types of Proof; namely, Provisional Proof, Definitive Proof, and Nitro Proof.

1989 Miller's Collectables Price Guide 1989–90 257/1 Double action revolver..with 4 in (10 cm) barrel, nitro proof, with a leather holster and belt.

1932 G. Burrard Mod. Shotgun III. xv. 323 A question which is frequently arising is whether an old gun which has never been nitro proved is safe to use with cartridges loaded with nitro powders.

1976 Shooting Mag. Dec. 63/3 (advt.) H. Holland Hammergun made in October 1872. Complete in fitted leather case. Recently nitro-proved, in fine condition.