Editing Aloe (section)

=== Chemical properties ===
According to W. A. Shenstone, two classes of aloins are recognized: (1) nataloins, which yield [[picric acid|picric]] and [[oxalic acid]]s with [[nitric acid]], and do not give a red coloration with nitric acid; and (2) [[barbaloin]]s, which yield aloetic acid (C<sub>7</sub>H<sub>2</sub>N<sub>3</sub>O<sub>5</sub>), chrysammic acid (C<sub>7</sub>H<sub>2</sub>N<sub>2</sub>O<sub>6</sub>), picric and oxalic acids with nitric acid, being reddened by the acid. This second group may be divided into a-barbaloins, obtained from Barbados ''Aloe'', and reddened in the cold, and b-barbaloins, obtained from ''Aloe Socotrina'' and Zanzibar ''Aloe'', reddened by ordinary nitric acid only when warmed or by fuming acid in the cold. Nataloin (2C<sub>17</sub>H<sub>13</sub>O<sub>7</sub>·H<sub>2</sub>O) forms bright-yellow scales, barbaloin (C<sub>17</sub>H<sub>18</sub>O<sub>7</sub>) [[Prism (geometry)|prism]]atic crystals. ''Aloe'' species are used in essential oils as a safety measure to dilute the solution before they are applied to the skin.<ref>{{Cite journal|last1=Orchard|first1=Ané|last2=Kamatou|first2=Guy|last3=Viljoen|first3=Alvaro M.|last4=Patel|first4=Namita|last5=Mawela|first5=Patricia|last6=van Vuuren|first6=Sandy F.|date=2019-01-14|title=The Influence of Carrier Oils on the Antimicrobial Activity and Cytotoxicity of Essential Oils|journal=Evidence-Based Complementary and Alternative Medicine|volume=2019|pages=1–24|doi=10.1155/2019/6981305|issn=1741-427X|pmc=6348851|pmid=30733812|doi-access=free}}</ref>