<?xml version="1.0"?>
<xsl:stylesheet version="1.0" 
  xmlns:xsl="http://www.w3.org/1999/XSL/Transform">

    <xsl:template match="/">
      <html>
        <body>
          <xsl:apply-templates select="PERIODIC_TABLE"/>
        </body>
      </html>
    </xsl:template>

    <xsl:template match="PERIODIC_TABLE">
      <h1>Elements with known Melting Points</h1>
      <xsl:apply-templates select=".//MELTING_POINT"/>
    </xsl:template>

    <xsl:template match="MELTING_POINT">
      <p>
        <xsl:value-of select="parent::ATOM"/>
      </p>
    </xsl:template>

</xsl:stylesheet>
