Though it won't always help, always remember to check "The Bottle Book" by
Richard Fike (1987)(for patent medicine bottles) and "Bottle Makers and Their
Marks" by Julian Toulouse (1972) for alcoholic and some other bottles.
 
According to Fike (p. 195) REGENTS//MACASSAR/OIL//FOR//THE HAIR  is a product
of Rowland & Son, London, adv. 1851. On page 194 he provides a size for the
bottle and indicates it is clear glass.  On the same page he also lists
  ROWLANDS/MACASSAR//OIL??No 20 HATTAN/GARDEN/LONDON//THE ORIGINAL/AND
GENUINE
 
A hair preparation introduced in England ca. 1793, by Alexander Rowland;
still available 1953 (Turner 1953); distributed 1929-30 by Fougera & Co.
 
Mike Polk
Sagebrush Archaeological Consultants, L.L.C.