Sala began publishing extensively in the disciplines of chemistry and medicines in about 1608-9, including a book of medications in 1624. He subscribed to corpuscular theory, asserting, for instance, that fermentation was a regrouping of elementary particles that resulted in the formation of new substances, an idea that was supported by Sala's experiments which provided evidence that the same substance persisted through a series of chemical changes, so that it could be assumed that minute atoms were the unchangeable parts that persisted through all the steps.
Sala would not let himself be misled by the illusions of the alchemists, as he asserts in many places in his works. In his treatise on the seven metals he reveals the gross artifice by which tin can be shown converting into silver: "Beware of the Crysopoeans who pledge to transform tin into silver. For [...] this crystal [silver nitrate] can be so cleverly conjoined with purified soda, unless the weight of the fallacy is detected," and also issues warning in "a brief demonstration of what vitriol is, or of what substances it is composed, and how much they deceive those who think that vitriol and water of vitriol can in fact transform iron into brass" Sala decomposed copper (blue) vitriol into copper ash, acid spirit (spirit of sulphur), and water, proving its decomposition through recombining the materials into the original vitriol. Likewise he synthesised sal ammoniac from the spirit of salt (hydrochloric acid) and the volatile salt of urine (ammonium carbonate). In Ternarius bezoardicorum he explicitly declares that he does not want to have anything in common with those of his colleagues "ensnared in vain hope" who still dream of the possibility of being able to obtain the philosopher's stone.