His caustic expression served as a catalyst to her boredom.
The kittens were a catalyst to crumbling the walls of tension that had been built between them.
Every chain of events starts with one push, a catalyst, the perfect mix of different elements that craft a path and make an outcome more likely.
It may be prepared by distilling fuming sulphuric acid, or concentrated sulphuric acid over phosphorus pentoxide, or by the direct union of sulphur dioxide with oxygen in the presence of a catalyst, such as platinized asbestos (see Sulphuric Acid).
Phys., 1838, (2), 69, p. 170), by the action of chlorine on a mixture of ethylene and sulphur dioxide, may also be obtained by the direct union of sulphur dioxide and chlorine (especially in the presence of a little camphor); and by heating chlorsulphonic acid in the presence of a catalyst, such as mercuric sulphate (Pawlewski, Ber., 18 97, 3 0, p. 765): 2S0 2 C1.
It will only combine with hydrogen in the presence of a catalyst, but combines with many other elements directly; for example, phosphorus melts and then inflames, antimony burns in the vapour, and mercury when heated with iodine combines with it rapidly.
Reinders (Ber., 1896, 29, p. 1369, 1899) have shown that the transformation is a monomolecular reaction, the velocity of transformation in moderately dilute solution being independent of the concentration, but proportional to the amount of the catalyst present (amine hydrochloride) and to the temperature.
In many cases it is found that hydrogen peroxide will only act as an oxidant when in the presence of a catalyst; for example, formic, glygollic, lactic, tartaric, malic, benzoic and other organic acids are readily oxidized in the presence of ferrous sulphate (H.