Examination of the cross-sections has shown that in the earlier phase he used exclusively cobalt blue, available from 1802, his habitual choice during the 1870's and early 1880's, but in finishing and revising the composition he used only artificial ultramarine which came in use in the 1870s.
A common misconception with this is that nits and lice are the same thing. In fact this is not the case, the truth is: Lice are the tiny grey or brown insects that are found in the hair. The lice are about the size of a small seed (i.e. Sesame seed) and cling to the hair staying close to the scalp which they live off.
If no dead lice are found and lice seem as active as before eight to 12 hours after treatment, the medicine may not be working. See a health care professional for a different medication and follow their treatment instructions. Nit (head lice egg) combs, often found in lice medicine packages, should be used to remove nits and lice from the hair shaft. Many flea combs made for cats and dogs are also effective. After the initial treatment, check, comb, and remove nits and lice from hair every two to three days.