Abbreviations. Only such as are in common use, along with accustomed signs should be employed, as: Э, 3, ℥, e, M, O, S, aa, ad, gr., gtt., ft., lb., et, ss, q. s., sig., cong., misce, mist., cap., chart., emul., pil., solv., sol., pulv., etc. The following should always be avoided: aconit. (for aconitine, aconitum), ammon. (ammonia, ammoniacum), aq. chlor. (aqua chlori, aqua chloroformi), chlor. (chlorine, chloral, chloroform), hyd. chlor. (calomel, corrosive sublimate, hydrated chloral), sod. sulph. (sodium sulphite, sulphide, sulphate), zinc. phos. (zinc phosphate, zinc phosphide), ac. hydroc. (acid hydrochloric, acid hydrocyanic diluted), ext. col. (extract colchicum, extract colocynth), sod. hypo, (sodium hyposulphite or hypophosphite), aq. fortis (for aq. fontis), etc.
Essentials. After having made the diagnosis, then carefully consider the medicines most desirable, their demanded quantities and number of doses, trying never to prescribe more than necessary. See that the doses are neither too large nor follow each other so often as to endanger life - smaller and oft-repeated ones always being advisable. Avoid combining in one prescription medicines that will form poisonous compounds, have physiological incompatibilities, or will favor chemical decomposition. Let prescriptions be as simple as possible, having the smallest number of ingredients that will secure the desired effect. Always read them over carefully before finally handing same to attendant, and rewrite rather than permit a visible correction to exist. Large doses should always be underscored with a heavy line by the physician, and when desiring certain prescriptions not to be repeated, he should so mark the blank with the two words non-repetatur. When incompatibilities are intentional they should be so indicated by a marginal note; when otherwise the pharmacist will consider it his duty and privilege to make the necessary correction or remedy.