Liquor Atropiae is an atropine-containing solution. The salt, solvent and specified strength remain necessary parts of identifying a particular historical liquid.^[ref]

Unguentum Atropiae is an atropine-containing ointment. Its semisolid vehicle defines a local formulation distinct from an atropine solution.^[ref]

For $ϵ\downarrow 0$, put $L=\log (1/ϵ)$. Taking a logarithm gives $x^2+\log x=L$, first implying $x\sim \sqrt{L}$. Substitution of $x=\sqrt{L}+d$ gives $2\sqrt{L}d+\frac{1}{2}\log L$ at first correction order. Hence $d=-(\log L)/(4\sqrt{L})$; substituting back and using the derivative of $x^2+\log x$ bounds the remaining root error by $O((\log L{)}^2/L^{3/2})$.

The propagation speed inferred from an effective path distance and the travel-time difference of corresponding features in two arterial waveforms. Path definition, synchronized timing and reflections matter; a pulse peak need not track an unchanged waveform.^[ref]

A historical arsenic-separation and recognition procedure associated with James Marsh. Volatile arsine carries arsenic away from a sample matrix and yields a deposit; stibine can interfere.

A historical deposition test using copper in an acidified sample. Deposits require further characterization because substances other than arsenic can interfere.^[ref]

The +3 oxidation state of arsenic. The actual aqueous species can depend on pH, hydrolysis and ligands; a bare ionic formula is an analytical shorthand.

Arsenic trioxide is the arsenic(III) oxide conventionally written $\mathrm{A}{\mathrm{s}}_2{\mathrm{O}}_3$. The formula expresses its elemental ratio; molecular units in some forms are $\mathrm{A}{\mathrm{s}}_4{\mathrm{O}}_6$.

This distinction separates an empirical formula from the structure of the actual species. Reactions involving arsenic trioxide depend on pH, dissolved speciation, and oxidation state, rather than on the oxide formula alone.

Arsenic trisulfide is $\mathrm{A}{\mathrm{s}}_2{\mathrm{S}}_3$, an arsenic-sulfur compound. Its crystalline mineral form is orpiment; amorphous forms have different structural order.

The distinction between a crystal and an amorphous solid matters for optical behaviour and material processing. The same nominal elemental ratio can therefore occur in materials with different local structure and physical properties.

Arsine is $\mathrm{As}{\mathrm{H}}_3$, a molecular hydride of arsenic with a pyramidal arrangement of three hydrogen atoms around arsenic. It is the arsenic analogue of Ammonia, although their chemical properties differ substantially.

The small molecular structure gives arsine a very different physical form from solid arsenic oxides or sulfides. This illustrates why an element's compounds cannot be assigned the properties of the pure element.

An arsenic compound contains arsenic chemically combined with other elements. Examples include covalent arsine, arsenic trioxide, and arsenic trisulfide.

The oxidation state and chemical partners strongly affect behaviour. Elemental composition alone does not specify volatility, solubility, or biological effects, so identifying an arsenic-containing material requires its chemical form as well as the amount of arsenic.

The permitted array indices for a length-$n$ array are $0,\dots ,n-1$ under zero-based indexing. A one-past-the-end index $n$ can describe an empty remaining segment but cannot be dereferenced. Proving bounds safety requires showing that every executed read and write uses a permitted index, including evaluations in a loop guard. A known target inside the array can sometimes supply a stronger loop invariant than an explicit bounds test.

The +3 oxidation state of antimony. The actual aqueous species can depend on pH, hydrolysis and ligands; a bare ionic formula is an analytical shorthand.

Potassium antimony tartrate is an antimony-containing salt with potassium counterions and tartrate ligands, historically called tartar emetic. Its composition includes both inorganic metal centres and organic coordinating groups.

The tartrate provides oxygen donor sites that bind antimony. This makes the compound an example of how coordination chemistry joins metal-ion chemistry with the stereochemistry and functional groups of an organic ligand.

The volatile antimony hydride that can give a dark antimony deposit and interfere in a Marsh test.

The sulfide with composition $\mathrm{S}{\mathrm{b}}_2{\mathrm{S}}_3$; the mineral stibnite and a freshly precipitated material can differ in appearance and structure.

An amphoteric antimony oxide used in descriptions of antimony extraction and solution chemistry.

The chloride historically called butter of antimony. Hydrolysis on dilution can produce oxychloride-containing precipitates.

A pentavalent antimony chloride whose solution behaviour depends strongly on hydrolysis and chloride concentration.

A class of anticoagulant heparin fragments whose effects include enhancement of antithrombin-mediated inhibition of coagulation factors. It is not interchangeable with every other anticoagulant merely because they share an intended effect.