  Gunasekaran et al (Pramana J. Phys. 75 683-690 (2010)) report to have grown
the nonlinear optical crystals urea thiourea mercuric chloride (UTHC) and urea
thiourea mercuric sulphate (UTHS). We argue that UTHC and UTHS are dubious
crystals and are not what the authors propose.
