"spirits of salts" meaning in Anglais

{
  "categories": [
    {
      "kind": "other",
      "name": "Locutions nominales en anglais",
      "parents": [],
      "source": "w"
    },
    {
      "kind": "other",
      "name": "Anglais",
      "orig": "anglais",
      "parents": [],
      "source": "w"
    }
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "noun",
  "pos_title": "Locution nominale",
  "senses": [
    {
      "alt_of": [
        {
          "word": "spirits of salt"
        }
      ],
      "categories": [
        {
          "kind": "other",
          "name": "Noms indénombrables en anglais",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Substances chimiques en anglais",
          "parents": [],
          "source": "w"
        },
        {
          "kind": "other",
          "name": "Termes désuets en anglais",
          "parents": [],
          "source": "w"
        }
      ],
      "glosses": [
        "Variante de spirits of salt (H₃O⁺ + Cl_⁻)."
      ],
      "id": "fr-spirits_of_salts-en-noun-rHswNzDf",
      "tags": [
        "alt-of",
        "obsolete",
        "uncountable"
      ],
      "topics": [
        "chemistry"
      ]
    }
  ],
  "word": "spirits of salts"
}

{
  "categories": [
    "Locutions nominales en anglais",
    "anglais"
  ],
  "lang": "Anglais",
  "lang_code": "en",
  "pos": "noun",
  "pos_title": "Locution nominale",
  "senses": [
    {
      "alt_of": [
        {
          "word": "spirits of salt"
        }
      ],
      "categories": [
        "Noms indénombrables en anglais",
        "Substances chimiques en anglais",
        "Termes désuets en anglais"
      ],
      "glosses": [
        "Variante de spirits of salt (H₃O⁺ + Cl_⁻)."
      ],
      "tags": [
        "alt-of",
        "obsolete",
        "uncountable"
      ],
      "topics": [
        "chemistry"
      ]
    }
  ],
  "word": "spirits of salts"
}