Many essential oils have more than 10% of hydrocarbons.
This is not a complete list of all oils and does not mean that if the oil is not on this list, that it is okay to use, this is a small example only:
Angelica 95%
Bay 30%
Bergamot 55%
Cajuput 40%
Carrot Seed 50%
Cascarilla 30%
Cedarwood 60%
Celery Seed 80%
Cistus 10%
Copaiba Balsam Oil 90%
Chamomile 15%
Citronella Sri Lanka 15%
Clove Leaf 15%
Clove Stem !5%
Costus 30%
Cubebs 70%
Cumin 50%
Cypress 70%
                              Oils containing Methyl Salicylate are toxic to cats.
Loosely think of methyl salicylate oils as aspirin to your cat. However unlike aspirin, methyl salicylate rapidly permeates the skin and can potentially constitute a risk situation in cases of high levels of exposure. The amounts resulting from exposure to floral oils and absolutes containing methyl salicylate is more insignificant e.g. ylang ylang and gardenia compared to those
which mainly comprise methyl salicylate such as Wintergreen and Birch oils. Use caution when these or any essential oil is used around cats.Methyl Salicylate occurs in several essential oils and absolutes e.g. ylang-ylang, gardenia absolute and is a major component of wintergreen and birch oils.
 
Natural Aromatic Materials - Odours & Origins, by Tony Burfield.

Tony, What really is in the hydrosol you buy? With regard to hydrosols, the position is further complicated. Where the pure hydrosol is taken, only the water soluble components of the oil should be present. Since monoterpene hydrocarbons have a very low water solubility, and oxygenated materials are slightly more hydrophilic ("water-loving") you would expect to see
more of the latter compounds present unless there are complicating factors operating. Thus in lavender hydrosol, we would expect plenty of linalol, linalyl acetate, terpinen-4-ol, and enhanced quantities of  lavandulyl acetate, octyl acetate etc. at the expense of say limonene, para-cymene etc. Amongst the complicating factors are the occurrence of micro-emulsions and solublilised oil droplets in the hydrosol itself, in other words the essential oil may not be homogenously dispersed in the separated distillation water, but present as a minor continuous oil (undissolved) phase, the composition of which  which is more representative of the whole oil than a truly solubilised oil. Complex micro-emulsion formation and other physio-chemical phenomena may further complicate the issue. In addition after a few days, microbiological and chemical changes will occur and may affect this balance to a limited extent.Also bear in mind some hydrosols on sale are not true
hydrosols, they are essential oils solubilised in water with a surfactant. Obviously the composition of these fake hydrosols will bear no relationship to true hydrosols.

Notes on one type of hydrosol: Hydrosols are a by-product of the production of essential oils, but often find their own local uses. For example, in the processing plant where production of Kewda (Champaca) otto and Kewda attar is manufactured in villages such as Paralakhemundi which are near to the coast bordering the Bay of Bengal in India, it is possible to produce some 18 litres of Kewda hydrosol by water distillation (known as Kewda water) for every 1000 blooms. In fact the male spadices of the Champaca flower (generally Pandanus odoratissimus L. , or Pandanus fascicularis  Lam.) only are employed, since these are the fragrant parts of the blooms. The resulting Kewda hydrosol is used to flavour confectionary, sugar syrups and local non-alcoholic beverages.

Other examples of hydrosols produced include those from Rose Rosa damascena and Lavender Lavendula angustifolia, although the employement of water distillation to produce hydrosols in the latter case causes loss of linalyl acetate, with a corresponding rise in  linalol and alpha-terpineol
contents.
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