688 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS instilled undiluted or diluted with water, and whether it was left in situ or rinsed out with water soon after instillation (Table I). Neither the neat product, nor a 25•o aqueous dilution, produced any sign of irritation in the eyes of squirrel monkeys. The monkeys were allowed out of their cages and they showed no difficulty in jumping round the room this seemed to confirm the absence of serious visual impairment. Exposure to oxygen and/or to uv irradiation did not increase the pro- duct's irritancy to the rabbit eye. Furthermore, this was not increased by sulphuric acid (at strengths up to •q/100) which was added to simulate atmospheric pollution. Another study involved the instillation into rabbit eyes of a saturated solution of sodium chloride, or 4•o formolsaline or the instillation of a 15•o solution of Teeoeol. The irritancy of these materials was not potentiated by the hairdressing. Definite irritation was, however, observed when rinsings were taken from the human head after normal use of the hairdressing, concentrated by freeze-drying and then instilled into rabbit eyes (Table II). This procedure was designed to allow for possible changes in the product after application to the scalp. Even under these conditions, there was still no real inflamma- tory response in the rabbit eye. However, transient corneal wrinkling or pitting was noticeable 1-2 h after instillation. This was most prominent 1-2 h after a second instillation had been made, 2 h after the first. Corneal pitting could not, however, be seen 24 h after instillation. Corneal pitting was also observed after duplicate instillations of a 20•o aqueous dilution of Table II Rabbit eye responses to hair washings 0.1 ml of five-fold concentrate six rabbits Hours after first instillation Hours after second instillation Effect 1 2 1 2 24 Pitting Slight 1 Moderate 1 l 1 1 Prominent 1 1 Inflammation Slight 1 2 Moderate 3 1 Normal 5 4 2 3

JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Figure 1. Pitting of rabbit cornea 1 h following instillation of a suspension of one part by'weight of powdered human scalp scales in 300 parts of a 20 •/o aqueous dilution of hairdressing micro-emulsion (duplicate 0.1 ml instillations 2 h apart). (Facing p. 688)